Wounds

Wounds is common passive unit ability introduced in Total War: Warhammer III and exclusive to single entities, i.e. units with one combatant, including hero  and lord  units.

Description in-game
"Even the greatest foes can be laid low with terrible injuries, and the greater the damage done, the less able they will be to effectively continue the fray."

Source

 * Total War Discord Q&A archive: your questions answered on Kislev and Khorne