When a unit with Endurance or Lifesteal takes damage, kill it.
Card sounds may differ from in-game as they get updated.
Endurance - Units with Endurance ready at the start of each players turn, so they can attack and still be ready to block during the enemy turn. Additionally, they are completely immune to enemy stun and exhaust effects.
Lifesteal - Units and spells with Lifesteal give you health when they deal damage, healing you equal to the damage dealt.