Comebacks

What are the biggest comebacks you guys have ever had? I suppose I'm obliged to start. I have 3 that are memorable, and one is a two-for-one.

1. Back when Riot hosted their RP tournaments, I was playing in an ARAM tournament. In the first game of the tournament, the enemy team had a massive early game advantage, so they destroyed us, leaving us with our inhibitor down at 8 minutes. Instead of giving up, the team managed to hold on with massive wave clear and held the game out until 45 minutes and we won the game. In that same tournament, in the finals, once again, we were destroyed early game, and had our nexus open at 12 minutes. Within 20 minutes, however, with some amazing teamfighting, we came back and won the game.
2. In the Definitely Not Dominion gamemode, the team was down 40 points to 480. The team was tilted, but due to so amazing Azir slides from myself, we came back and won the game.
3. Open nexus, one hit left, the final teamfight right at Baron pit, a pentakill from our Jayce, amazing! Your turns! <3