Card sounds may differ from in-game as they get updated.
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.
Revenge - When a card with Revenge dies, it permanently loses Revenge and gains Destiny and then it is put randomly into the top ten cards of its owner's deck.