Favorite spells?

[DGDobrev]

For me:

Target + Stone skin combo - battle winner
Evlin - the undead resurrection spell
Death Star - combine with high intellect and you can beat up impossible enemies with ease
Armageddon - combine with Paladin hero with Resurrection skill lvl 3 and Black Kinghts - Judgment Day Paladin FTW

These are the spells I usualy use - unless I'm going for the prerequisites for the medals.

[TemjinGold]

My impossible mage with a 1-troll army loves Fear.

[Zechnophobe]

Phantom is amazingly good. Phantom Ogres can lock down an army pretty good. Phantoming dryads is a surplus of thorns and a lock down on all level 3 and under units. Phantom Red Dragons for significant damage.

Fear is also pretty awesome, especially for a mage. The duration increases, but cost doesn't, when you level it up. This means you can often keep enemy forces locked down for a long time with it. It also prevents an enemy hero from casting on the feared units turn.

Helplessness. It completely dominates against basically any level 5 unit. Huge penalty to armor (Often causing double or tripple damage against the target) and the negative morale for a long duration is good too.

Summon Phoenix: In AP, the 'burning' effect decreases morale. You can also get summon phoenix fairly early, and it has something like a 90% chance to burn targets, so you can use it for good damage, massive debuffs, and as a tank (If you get it to level 3 early). It also is cheaper than any other summon spell.

Stone Skin: Resistence AND defense? Sign me up!

[Zhuangzi]

Spells I use all the time...

Distortion is the school of Magic I use the most:

Mass Haste (normally on turn 1)
Stone Skin
Trap
Target
Phantom
Turn Back Time

Turn Back Time is just insanely good. I normally don't use level 5 creatures, so I only need level 2 of this spell. I have had a lot of success with Hasted Horsemen charging straight into the midst of the enemy, soaking up two turns of damage (enough to nearly kill the stack sometimes), before casting Time Back Time at the level of turn 2.

Order:

Helplessness
Healing (for level 5 units)
Dispel (we all know why this spell is necessary in AP )

Chaos:

I don't bother with Chaos as a Warrior due to low Intellect, but as a Mage with 40 Intellect and Higher Magic, it's a different story.

Fire Arrow (5 mana, even at level 3? )
Ghost Blade (10 mana but no burning. Good for bosses)
Fireball
Fire Rain (if I can find it)
I also use Sheep and Demon Portal sometimes.

[Zechnophobe]

It is weird, but I almost never use damage dealing spells, opting for control ones. Sure, you can do a lot of damage... but Fearing a target for 5 turns basically 'kills' it.

[Elwin]

I think that most common spell books say for themsleves :
Frol left to right:
Mage,Warior, Dark Paladin
ONly one note : batlte cry doesnt count xS it was just spamming to get medal xD

[Newbie1234]

Most of the best spells have already been stated, but I thought I'd add a couple of other ones that have so far been ignored.

Calm Rage - Very important in boss fights to keep your Mana high since you aren't allowed to use the Dragon.

Awaken Dragon - Great spell for obvious reasons. I often use it to open two Treasure Chests in a round.

Mass Battle Cry - A surprisingly useful spell for keeping losses down against enemy high-intellect Heroes. On the last turn, cast this, do your Resurrections, and finish off his units before the opponent gets to cast. It won't be used too often, but it's a good spell to have in your arsenal nonetheless.