Card sounds may differ from in-game as they get updated.
Lifesteal - Units and spells with Lifesteal give you health when they deal damage, healing you equal to the damage dealt.
Overwhelm - A unit or spell with Overwhelm will deal any excess damage to your opponent on your turn (does not work while blocking).
Summon - Does something when played
Nightfall - The first Nightfall card played in a turn makes it Night and extends it by a turn for each player.
Night - When you start a turn at Night, draw an additional card and take 1 damage.