Card sounds may differ from in-game as they get updated.
Aegis - Aegis protects a unit or player from one enemy spell or effect. It doesn't block friendly effects, nor does it stop battle damage from Killer attacks, Relic Weapons, or normal attacking and blocking.
Deadly - Units and spells with Deadly kill any unit they damage, regardless of health. For example, a 1/1 with Deadly can kill a 5/5 attacker.
Lifesteal - Units and spells with Lifesteal give you health when they deal damage, healing you equal to the damage dealt.