Blue and green can potentially untap him several times in a single turn, and all three colors offer enough proliferate and counter-doubling to potentially ultimate a planeswalker when you first summon it (and thats without a Doubling Season)
A white-blue-black that costs four total mana, hes a 3/3 with incredible abilities for being that mana-cheap, including First Strike, vigilance, AND menace
When a card or effect is activated that would destroy a card on the field (Quick Effect): You can banish 1 Zombie monster from your GY
I should be saving up and planning for a low expenditure life, but the past week Ive been spending all my money on these beauties
its airbending trigger also removes threats, albeit temporarily, or you can use it to pseudo-flicker your permanents
The Gamma playtest even tracked league cards with a tiny unicorn stamp on the back