Deadly - Units and spells with Deadly kill any unit they damage, regardless of health. For example, a 1/1 with Deadly can kill a 5/5 attacker.
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.