Summon: Play a power card of your choice from your deck.
Empower: Play a 1/1 Humbug with Flying.
Card sounds may differ from in-game as they get updated.
Empower - Does something when you play a power card.
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.
Summon - Does something when played