If were willing to pay for the long game and recast creatures, Boomerang effects will also be very helpful
If your opponent doesn't have removal, it becomes a headache to deal with as you will be prevented from your life total reaching zero, and require your opponents to win through other means
Cast it on the turn you intend to go off and your opponents will have a hard time stopping you from taking the game
Self-Destruct, for example, would have been a nastier component of the already rampant Mono Red, especially with the knowledge that one of the winning moves for it was to blow up a Heartfire Hero using it
Every creature you cast adds a +1/+1 counter to Animar, reducing the cost of your next creature by one colourless mana
So, the Gateway Box basically holds your hand through the first round by controlling the first seven cards that come into your hand