In Warlords Battlecry 3 I've been experimenting with the various spheres of magic and the abilities. I first started off with the various magics that deal in summoning. With each level, summoning spells allow you to summon more units at higher levels than previously possible. A great danger for summoning, is that those using the Poison sphere, can cast the "Poison Gate" spell, which poisons all units summoned. The duration varies with the level of the spell, but it is not good.
Necromancy
I made an Undead Necromancer and trained him until he could cast all 10 spells at level 10. Necromancy isn't exclusive to the undead, but they can utilize it best and get a synergy bonus during hero creation, boosting your base stats. Necromancy is good for flooding the land with hordes of undead, achieving victory by overrunning your opponents with decent leveled units of various power. This is very easily achieved if you cast the "Black Portal" spell, which allows you to summon more undead units than normal at one time. I never raise the dead without it.
The only units not primarily serving as combat units, that you can summon, are zombies. These are the builders of the Undead race. They do crushing damage, are resistant to all physical damage but are weak to all elemental damage. They also get the disease ability, which can infect enemy units if they attack. Targeting builders is not uncommon, as they are the backbone of every fight. They are slow moving but are actually one of the toughest of all the builders, not to mention cheap when producing them from the graveyard. They can be upgraded to scavenge resources from dead bodies, but this ability is wasted because the chances of a zombie coming near a corpse is slim to none. Whn it's raining, they get a combat bonus, so using the "Darkstorm" spell can make them formidable in the beginning of a fight.
The weakest of the undead combat units, at level 1 of course, can be summoned at level 13, they are skeletons! Unfortunately they can't attack flying units, a vulnerability that easily leaves them susceptible to daemons, griffons, unicorns, harpies and the like. On the plus, you can summon 12 of them at a time when you have at least 10 skill points on Necromancy, so winning by sheer numbers is easiest with them when you set their behavior to rampant.
Raising wights turned out to be disappointing. Unfortunately they only come in at a maximum of level 8, but being supposedly better infantry they aren't stronger than the skeletons.
The "Raise Champion" spell was fun. It gives you the choice of summoning 4 advanced/elite units. The first of the 4 is are shadows. They're the advanced version of the wraith unit, which does cold damage and steals experience from every unit it kills, making it easy for them to level up. And like the skeletons, you can summon 12 of them at once. They come in at level 8 but they make up for it with unique abilities. The big difference is that shadows can attack flying units and when they attack they have a chance of freezing their victims, drastically reducing their movement speed and attack speed. Enemy heroes usually try to flee when this happens, making them easier targets. Sometimes they give up and just let the shadows kill them. Valuable units indeed!
The 2nd of the 4, liches, are the Undead spellcasters. They attack by conjuring up fireballs and naturally, they are ranged units so they get the first shot on all close combat units and most heroes. They come in at level 8 as well however you can only summon 4 at a time. The kicker is that you can use them to garrison your towers, giving them fireball attacks and a large power boost. Essential to protecting your base from enemy attacks!
The 3rd of the 4, vampires, are the generals of the Undead. Being generals it means they can convert mines just like your hero, which is good when you want to cover more ground when gathering resources. Vampires come in at level 8 and you can summon 4 of them at once. They can attack flying units as well but they aren't exactly heavy hitters. What they lack in attack power they make up for with the "Vampirism" ability. They steal health when they attack. It helps prolong their unlife and can even allow them to overwhelm many units. Their dark magic can also be helpful. They can summon bats to aid both himself and you. Bats aren't a huge threat, but they're good for scouting or distracting enemies while the vampire or yourself retreats to safety. Of course, like all magic, mana has to regenerate between uses, unless mana regeneration is high. I don't particularly like them though.
The last of the 4, the Doom Knight, is my personal favorite of the Necromancy sphere. Doom Knights are elite infantry units, capable of attacking flying units as well, but also very capable units. It helps that they cause Chaos. They come in at level 8 and you can summon 4 of them at once. A full party of these, totaling 32, is enough to easily overrun enemy bases. Their resistance to piercing damage makes them a challenge for heroes, as most of the time enemy heroes deal piercing damage. Like most undead units however, they are weak to crushing damage, so ogres, air/earth elementals and especially most siege units can get rid of them rather quickly.
If that isn't cool enough, you can use the "Call of The Dead" spell to raise the bones of any units in your command radius, friend or foe, to serve you as skeletons! It's good for turning the tide of a battle when you're on the ropes. Along with that, the "Strip Flesh" spell let's you turn enemy infantry into skeletons, drastically weakening them at the same time. Like all undead units, they gain a combat bonus at night, but are weakened during the day. This is good though because with the "Darkstorm" spell, you can change the time of day to night, as well as start a bone chilling downpour. In addition, you can buff your units with the "Vampirism" spell. This gives units in your command radius the ability to steal health when they attack. This can make all the difference in a fight, sending enemies running, or to their deaths where they can serve you. The downside to Necromancy is that there is only one direct combat spell, which is good for assisting your hero when he's under attack, "Ring of Ice." This spell send out a small shockwave of ice to hurt any buildings or enemies that it reaches. Many units are weak to cold damage so this can save your skin (or lack thereof.)
Summoning
The Summoning sphere is somewhat similar to Necromancy, in that it has a portal spell, "Circle of Power" to assist with summoning. The Summoning sphere however has a different variety of units that you can summon as well as a few non-summoning spells that can save you in the nick of time. In particular, it allows you to summon daemon units. Daemon heroes get a synergy bonus if they are a Summoner, so it is ideal.
Like Necromancy, you can summon builders. Since this summons Daemonic units, you get yourself the Quasit. Quasits are easily some of the best builders out there because their high resistance, armor, decent damage and speed (for basic units,) combined with their Poison ability, lets them go toe-to-toe with basic infantry. Their good for building your base and if need be, defending themselves from basic infantry. Unfortunately like most builders, they can only attack ground units. At most you can summon 12 of them at level 8.
Next in line are imps. They're basic missile units, which do cold damage but are also flying units, so basic infantry and some siege units can't fend them off. You can summon at most, 12 of them at level 8.
The Summoning sphere is a multipurpose magic, as you can see with the "Eye of Oros" spell which summons floating Eyeball units. These aren't daemon units. They are actually plague units. They have no combat capability but they serve as excellent scouts. They have high speed and can travel on water as well. close combat units can't keep up with them. Setting their behavior to scout will send them out to search for the enemy while avoiding combat. You can summon 12 of them at level 8 I believe. I could be wrong about that though, my memory is a bit fuzzy. They are very useful.
The "Soulharvest" spell summons a group of succubus. They're basic flying infantry. They are handy because they turn all units they kill into souls. Some Daemon units have the unique ability to eat the souls of their enemies, increasing their experience or if they are a spellcaster, restore some mana. Daemon heroes can restore mana by eating souls.
The pinnacle this sphere of magic, is the "Daemongate" spell. This summons Daemons, advanced flying infantry. They do double damage against "good" aligned units. They can summon imps, restore mana by eating souls and cause Chaos, which nullifies all positive bonuses of opposing units as well as reducing both the armor and resistance of opposing units. The good resistance, armor and damage of these units make them fierce. Not to mention their ability to summon imps can shield him from anti-flying units, or just add to the devastation of this unit. You can summon a total of 4 of them at level 8 I believe, maybe level 12 or 13. I don't quite remember.
Aside from that, Summoning magic has a few other perks. "Phanton Steed" buffs your cavalry units armor, speed and resistance. This helps protect them against crushing damage, which they are weak to. The "Blink" spell can be a lifesaver. It teleports you a short distance away, which is good when you're in a bind, like being surrounded by enemy units on all sides. The downside is that where it takes is completely random, so there is the possibility that it could send out of the fire and into the frying pan, so to speak. It's kind of a risky move, but worth it when facing death. Even more useful for escape is the "Home Portal" spell. This sends you to where you first spawned on the map no matter how far away you are. I would use this to escape rather than "blink" if you aren't at your own base, plus it saves you a potentially long walk back to your base, avoiding any danger. Finally there is the mighty "Banish" spell. This instantly kills all extra-planar units, such as daemon units, elementals and archons. Unfirtunately, this effects your own units as well, so if you aren't traveling alone, you should use this only when absolutely necessary. Higher level units might resist it, but most units below level 14 are defenseless against it if you can cast it at level 10, which requires 100 skill points on Summoning.
Illusion
Easily the most pitiful of summoning magics in regards to combat, is the Illusion sphere. It summons the weakest of creatures and has no spell to assist in summoning, so summoning is not it's strength. I use it for it's transformative capabilities instead. Users of the Illusion sphere can summon illusionary troops, which best serve as scouts or diversions. Illusionary units deal a pathetic 1 damage at all levels, have embarassingly low armor and resistance, but worst of all, low health. Aside from it's ability to summon Shadows and transformation spells, it is almost entirely useless.
The "Spectral Horde" spell summons illusionary versions of whatever the basic infantry for your heroes race is. I made a Minotaur hero because they are excellent warriors with the unique ability to recover health by eating small animals such as sheep, seals, penguins and geese which roam the map aimlessly. The plus side is that you can summon a ton of these guys at once, 24 if I'm not mistaken. The duration of the spell is directly proportional to the level of the spell. At level 10 it can last a long time unless killed. They're good for roaming the map, scouting ahead. Put a group of these guys on rampant and they'll uncover a lot of the map before they die off.
The "Dragonfear" spell summons an illusionary dragon, only 1 at a time, which can cause fear in opposing units. Fear forces them to run away from the dragon. It is a flyer that deals splash damage and what dragon you summon depends on your race. Each type of dragon has a unique ability: Fire can burn units, Frost can freeze units, Swamp can reduce armor of opposing units, and Dracoliches drain experience from opposing units. For this spell, the Dracoliche's ability is wasted since illusionary units cannot get stronger.
"Call Shadow" summons a horde of Shadows, just like necromancy. However usually the duration and of the spell and number of Shadows summoned per use is dramatically lower than if it were summoned via Necromancy because the Undead can get abilities that increase the effectiveness of their own summoning. On the upside, you can use the "Light/Darkness" spell to change the time of day, increasing the combat of your Shadows just as Necromancers can.
"Shadowform" increases the armor, speed and resistance of your hero just as "Phantom Steed" does for users of the Summoning sphere. "Scare gives your hero the ability to cause fear, which admittedly can be helpful against units that aren't immune to psychological effects. "Light/Darkness" changes the time of day between night and day, but can;t affect the weather. It's handy if you're fighting an enemy that gets a combat bonus from a certain time of day. The "Awe" spell gives your hero the ability to cause awe, which halves speed and bars ranged attacks. Used properly it can be a burden on your enemies. "Invisibility" however is very useful! You can travel the map alone and unseen, ensuring your safety from attack until you yourself attack, cast a spell or try to convert a building.
The highlight of this sphere of magic however are the last 2 spells. "Mutate" allows you to transform enemy units into harmless animals! This is perfect if you're hero is a Minotaur because he can then feast on what used to be enemy units to regain his health. Very fun! "Transform" lets you transform your own units into different units, largely random. The higher level you cast this spell, the better units they become. Not to mention the level of your keep, the main building of your base, effects it as well. If you have a level 5 keep, you can change builders or basic infantry into elite warriors, even general units! This lets you create powerful armies at a low cost of resources!
Use it the right way and you can turn your enemies into food while drastically upgrading your own units! Not to mention if you have any trolls, they can pick up the sheep made via "Mutate" and throw them at enemies for devastating damage! This also applies for catapults which can launch cows at your enemies, lol!
Nature
The Nature sphere is easily the hallmark of the summoning magics. Wood Elves get Nature magic by default and a synergy bonus to it if your hero is an Elementalist. So I created a Wood Elf Elementalist. Boy do I have fun with this combo! I hardly have to lift a finger to decimate my enemies!
Combining Nature magic with the right abilities, like Elemental Lore, let's you summon the most powerful units around, aside from Titan class units. "Summon Sprite" let's you summon a Sprite, a basic Fey flying infantry unit. It's fast attack power makes up for the fact that it is relatively weak, like most Fey units. You can summon either 8 or 12 of these at once. I don't remember.
"Summon Unicorn" let's you summon a unicorn, just 1 at a time. It is a Fey cavalry unit that can cast 2 healing spells. I feel they best serve as healing units rather than combat. Like any cavalry unit, it can't attack flying units.
"Summon Treant" let's you summon a Treant, the advanced builder unit exclusive to the Wood Elves by normal means. It has an impressive build skill of 15, nearly twice that of any other builder and it serves as a good infantry unit, dealing crushing damage that is superior to all other builders! These guys are hands down the best builders in the game, despite the fact that they can't build walls or towers to protect your base. You can summon just 1 of them at a time at level 8, but these guys can be dangerous! They can even attack flying units! In addition, if you managed to build any Ancient Treants, they naturally have the ability to split into 2 Treants upon death! Pretty neat if I do say so myself.
The very best of all summoning spells however is "Elementalism"! This lets you summon any of the 4 elementals in the game, 5 at a time even! I myself can summon any of the elementals at the maximum level for non-hero units, level 20! Air Elementals travel very fast, do splash damage and deal crushing damage! They are close combat units but boy do they do it in a big way! They can also travel on water, which gives them an edge. Fire Elementals are ranged units that shoot fireballs. They also have the ability to burn enemy units. Of all ranged units, I'd say they're second only to Water Elementals. Earth Elementals are deadly! They deal crushing damage, which is good for tearing down enemy buildings. And to make it more terrifying, they have the unique ability to deal quadruple damage on buildings! My level 20 ones deal a base damage of 98. That's 392 damage to buildings, making them capable of one-shotting most buildings! They may not be capable of attacking flying units, but they made up for it 10 times over! Water Elementals are in my opinion the best of the bunch when fighting enemy units. They are ranged units, but have less range than fire elementals. They deal cold damage and also do the most damage against enemy units. My level 20 ones do about 119 damage before any weaknesses or resistances are taken into account. They can also travel on water, which makes them more deadly against infantry and heroes because they can remain out of reach while attacking. I can decimate an entire map with just 5 of my level 20 elementals. I don't even have to move to win.
Summoning spells aside, the Nature sphere has some useful spells. "Gemberry" heals your hero and nearby units. "Entangle" decreases the speed of all enemy units, which is great for preventing your enemies retreat or for allowing you yourself to retreat. "Shillelagh" increases the combat of your hero. This can make all the difference in a fight. "Wall of Thorns" let's you instantly produce a wall at the cost of mana rather than resources like stone or gold. Use this properly and you can secure your base pretty well against enemy attack or even seal the enemy within a certain area of the map! "Call of Lightning" is the 1 direct combat spell in the Nature sphere. It does electrical damage by striking all enemy units in your command radius with bolts of lightning. Very handy against large groups of enemies. "Change Weather" is easily the best among all spells that affect the weather or time of day. It allows you to change the weather to either 'Fine' or 'Rain' and the time of day to "'Day' or 'Night'. This is good because Wood Elves get a combat boost in 'Fine' weather. Not to mention you can take away combat bonuses from your enemy.
Other spheres of magic, such as Pyromancy or Poison have 1 or 2 summoning spells, but they don't deal exclusively in summoning, so I didn't include them.
If you want a hero that conquers via summoning, I recommend Nature magic above all the others. If you want a warrior that can hold his own, I suggest Illusion magic because it is difficult to survive without some kind of magic and Illusion magic is in my opinion the most useful for a physical combat hero, since if a Minotaur, he can end up literally eating enemy troops for health and making terrifying warriors of the wimpiest of units, as well as giving himself a few useful buffs.