Im using my
High Gravity Bronze deck, which is Mono Gravity, to beat AI4 pretty decently, although it was designed to fight Bronze league initially. It uses a Nymph, but its not really necessary, just helps for some EM.
Problem about AI4, which may make them hard is, when they have less 3 cards in hand, they will double draw. So there is a bigger chance they will draw something to trouble your strategy. Sometimes looks like they just draw what they need. Maybe something to clog their hands can work. Something like a quanta denial (using quicksand), or Nightmare. Or a functional (protected?) Eternity in early game.