Even though its ability works completely in context with the rules of MTG, it was likely made an acorn card so you could only partner it with other Unfinity commanders
Thats a Vending Machine promo, so Works for me
(A creature with first strike deals combat damage before creatures without first strike.) Welcome to the Legion
Fast mana from Sol Ring, Ancient Tomb, Skirk Prospector, and Jeska's Will help you to cast key pieces early, while Lightning Greaves, Swiftfoot Boots, and Thousand-Year Elixir make sure that Krenko can tap right away and survive removal
Resplendent Marshal is an example of a pushed constructed card for tribal synergies, and that's probably the reason why it's a mythic rare
I had a similar thing at a draft the other day when the Reanimator player got hosed by Scavenging Ooze