Aspiring Champion and Rukarumel on the battlefield (Rukarumel with "Demon" chosen).
Aspiring Champion does not have summoning sickness, and cannot be blocked by an opponent.
({G} magic symbol) available.
Steps
Cast Sylvan Tutor by paying ({G} magic symbol) , searching your library for Blightsteel Colossus and putting it on top of your library.
Deal combat damage to an opponent using Aspiring Champion.
Aspiring Champion triggers, causing you to sacrifice it, then reveal Blightsteel Colossus from the top of your library and put it onto the battlefield as a Demon due to Rukarumel, Biologist, then causing Blightsteel Colossus to give each opponent eleven poison counters.
Each opponent loses the game as a state-based action due to having ten or more poison counters.