It is one of the most heavily disliked disciplines in Erfworld, perhaps second only to Carnymancy in the amount of vitriol aimed at its casters.
Uncroaking deceased units.
- Uncroaked Leader
Providing combat bonuses to uncroaked units in the stack, as well as leading them in Dance-Fighting.
- Sense Life
Croakamancers have a natural ability to sense life in other units, as demonstrated by Wanda in Book 0. They have a much stronger sense over dead bodies, to the extent that Wanda can give the precise number of each type of dead unit in a hex.
Croakamancy has significant limits. Uncroaked units decay over several turns before they rot down and disintegrate. They also lose a lot of their higher brain functions: Casters lose their magical abilities, warlords lose a great deal of their initiative and command skill, and regular units lose pretty much all trace of their identity. However, most specials are maintained: An uncroaked warlord can still lead to some degree, and uncroaked flying units can still fly.
Some units, such as Wiener-Rammers, cannot be uncroaked.
The amount of time and attention a Croakamancer invests in uncroaking a unit has a significant effect - a mass of units uncroaked in a hurry will only last a few turns, but an individual or small group carefully revived can last a very long time indeed.
Real World References
Necromancy is the magic of the dead. In the real world, it has most often been used as a form of divination, attempting to extract knowledge from the deceased. In fantasy, necromancers will frequently enslave the souls of the dead to draw power or to animate their corpses to form armies of zombies.
It is likely that constructed units, such as golems, cannot be uncroaked.
It seems that uncroaked units cannot be chief warlords (judging from the need for a new Gobwin Knob warlord in Book 1). Another possibility is that their leadership bonus decays so quickly that it's not worth using them).
With the Arkenpliers, Wanda is able to Decrypt units - to bring back the dead with all their abilities and most of their memories intact, but loyal to the caster and her side. Many casters believe this takes Croakamancy into the realm of Life magic, which is normally its antithesis. Many casters find this to be unnatural, and thus, wrong.