Tannuk, Steadfast Second Tannuk, Steadfast Second warp speeds, hyperdrives, or whatever other science reference you want your red creatures and artifacts
Blood-Chin Fanatic Similar to but better than Barrage Tyrant, Blood-Chin Fanatic is restricted by only being able to fling your warriors, but it also gains you life and is cheaper to activate than Barrage Tyrant
So, my opponent attacks me with the 3/3 [c]Radha, Heart of Keld[/c], a creature with first strike
Honestly, I feel that Karn is very overrated right now
Whenever this creature deals combat damage to a player, that player exiles the top two cards of their library
Big Score discards one, draws two and then makes two Treasures, I also tossed in the other three Treasure makers