Interesting series.
My ideas:
: One of the owner's creatures loses airborne per turn, randomly (synergizes with wings)
: Burrows up to three of the owner's creatures as long as it's in play, attack of 3(4)+ (halves damage from random creatures, deals 1 damage with shield out)
: Inflicts 1 point of damage to surrounding creatures, attack of 2+ (can weaken tough creatures, should have higher HP due to fire shield)
: Generates a card in the owner's hand after attacking, maybe attack of 3+ (can "nightmare" the opponent, card can be either copy of itself, relic, or a random card matching their mark)