Some spells take multiple turns to cast. For strategic spells this means the spell will take multiple turns before being unleashed. In tactical combat, spells with casting time take additional actions before they can be cast. If a unit casts fireball, which has a casting time of 1, the fireball will go off on the unit's next action. Plan your spells well: you may be sacrificing actions to cast them, but they can be devastating when they go off. If a unit is killed while preparing a spell, the spell will be canceled, so protect friendly casters and target enemy casters.