Slime Against Humanity will already be your primary source of creatures, and if you're willing to play without instants and nonland permanents, you'll be able to access Umori as a 101st card
Though exiling four cards a turn sounds like a lot of your deck gone, lets do the math: 100 cards, minus the commander, minus your opening seven-card hand, minus four draw steps by the time you cast this, leaves 88 cards in your library
the types of the Legendary Beasts Entei, Suicune, and Raikou which Ho-oh is often associated with
My fellow Magic: The Gathering loving Whovians, here's a deal worth your, er, time : the bundle pack of all four MTG Doctor Who Commander decks has an unprecedented 31% knocked off the price for Amazon's Prime Day celebrations - that's 58 bucks, taking the cost from $187 down to $129 (around $32 per deck)
Academy Rector (T1, Ext, S, Block) Ah, meat and potatoes time
This is one of the best blue creatures MTG has to offer because its got Flash