Against Garruk you either need to keep the board very clear, kill him or at least keep him away from 4 loyalty
The enrage mechanic also flopped because it was only very good against Red and Green
Ideally, you want to use this to temporarily subdue an enemy threat
Enchantment Color tag templates(None) Goblinslide Whenever you cast a noncreature spell, you may pay
If Donatello, the Brains and Splinter, the Mentor are your commanders, your deck may contain cards with blue and/or black in their color identity, but not cards with red, green, or white
For another, because you dont want to be sharing messy work with the world if you intend to land jobs from players that require legality