Lethos in Heroes 5

Enemy units may enter the combat already poisoned, chances depend on hero level.

Lethos is considered a very useful ally due to his ability to win a battle before it starts. Though he has served many decades, his intimate knowledge of the more exotic poisons and diseases remains undimmed. Enemy troops approaching the field may feel the effects of Lethos's spells and concoctions even before the fighting begins, wise enemies have been known to start their attack by retreating.