Onslaught: You and one of your other units each get +2 Health.
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.
Onslaught - Does something when played if you or any of your units have attacked this turn. This includes standard attacks as well as Killer and Relic Weapon attacks.