More about the doubly knocked off cards

ABILITIES ON CREATURE/CHARACTER CARDS
Flying (can only be blocked by other flying creatures and characters)
Mounted (can only be blocked by other mounted or flying creatures and characters)
Sly (hexproof)
Survivor (must be killed twice)
Trained (bonus when equipped)
Betrayal (control opponent's creatures and characters for x turns)
Aquatic/Aerial/Terrestrial

ENCHANTMENTS, SORCERIES, INSTANTS
WORDS (enchantments):
As High As Honor
Ours is the Fury
We Do Not Sow
Hear Me Roar
Unbowed, Unbent, Unbroken
Winter is Coming
Fire and Blood
Family, Duty, Honor
Growing Strong

OTHER ENCHANTMENTS
Water
Sky
Land
Flight
Mount
Sly
Survivor
Training

INSTANTS
Betrayal
Backstab
Slaughter
Leap
Smuggle
Golden Crown

SORCERIES
Chasing Cats (look at target player's hand)
Raise Dead (target creature or character from graveyard enters the battlefield under your control and gains haste and +3/+1. this creature or character returns to owner's graveyard at end of turn.)
Birth Shadows (not exactly sure what this one does yet, but it seems like a perfect sorcery)

Thoughts in the comments please. :)