Misty Rainforest (and any other blue or green fetch), Breeding Pool, et
I also chose not to include Wormhole Serpent for now, but that could legitimately get slotted into this deck in place of anything you don't already own, because it's a huge bang for your buck
While not as powerful as the destructive spells of white and black, reds damage has the flexibility to burn the opponent as well as their cards, making it hard to hold off forever
Astarion, the Decadent is also terrifying when you have effects in your deck that cut a player's life in half, since doing that twice will kill them
Erebos, God of the Dead provides some nice card draw/life loss
Ive done some absurd things with this, like casting a Surge to Victory which went on to combo off with my Ephemerate and my Aurelia, the Warleader