This deck is much more focused on creating an overwhelming board presence than doing it fast
Getting multiple activations to kill again each turn is crucial, so I recommend Thousand-Year Elixir, Illusionist's Bracers, or Battlemage's Bracers
3 mana for a 3 loyalty planeswalker is also an excellent rate, allowing you to play Aminatou early for access to an extra card in a pinch, providing easy setup of an inexpensive permanent with a relevant ETB ability and Aminatou on the same turn, or simply letting you play Aminatou late with mana up to protect it from countermagic or removal
Both can generate lethal board presence in a single turn cycle when your draw engines are running
While you lost out on deathtouch here, you do get to gain life, which can trigger a bunch of effects
Given how game-winningly nasty that ultimate, might I suggest Green for the counter adding and manipulation of Doubling Season et all