Great tempo gain through lasting board position and life gain push them over the edge of reasonable power
That last token is nearly free as well as you don't need to buy it back if it is making fatal
While this means the opponent will see it coming and not play out additional three-drops, it also means that on the turn your sweeper resolves, youll have mana up to deal with the next threat they play, or the four-drop that they deployed on the turn you played out your Sphere
He also has the tie-into-life-loss of the guild's later mechanic we see, so there's a strong flavor there
You start with 300 slots, and can expand inventory slots from quests, events, battle pass rewards, or even by paying Gil
Standard is way too fast for this, and Commander has plenty of better options