Kaito, Bane of Nightmares Kaito, Bane of Nightmares is the only planeswalker ever with the ninjutsu ability, and one of the few that can attack as a creature, an ability usually present on Gideon planeswalkers
There are 54 other Mutants in Simic that are legal in Commander
You could discard a Wonder to Mongrel/'Moeba/Compulsion and then have a flying horde
Grafdiggers Cage Grafdigger's Cage has lots of utility
The printer accidentally used different corner rounding dies for the second run, resulting in Alpha cards being noticeably distinct in shape and appearance from Beta cards and all subsequent cards
Mondrak, Glory Dominus's ability to double any token that's created under your control justifies the high price, but it becomes an even more fiscally sound investment when it gives itself an indestructible counter to become an unmovable threat