Please post PRO tips here for a noob :)

[Pug of Stardock]

There is a Resurrection spell in the game and there are other units that can resurrect fallen troops.

Finding spells is based to a large extent on luck and you won't likely find this spell until much later in the game.

Units that can resurrect include Paladins and Demonologists. Again, when and where or even if ever, you find these units is luck dependent. Also, these units cannot resurrect every creature in the game. For example, Black Dragons and, AFAIK, Ice Dragons and Ice Spiders cannot be resurrected by Paladins or D-ologists.