Flying, Lifesteal, Aegis
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 attack and blocking.
Flying - Flying units can only be blocked by other flying units, but can block ground units normally. They can also be directly attacked by Killer units and Relic Weapons.
Lifesteal - Units and spells with Lifesteal give you health when they deal damage, healing you equal to the damage dealt.