So many games, too many comebacks to remember specific ones. One that stayed in my mind though was a game where we had 2 leavers. I asked the other two remaining players to not give up but give them a good fight and they were onboard. I was on AI-herding duty, watching my positioning carefully to keep them safe but effective. After a lot of hard work we got very close to winning but just barely lost the final teamfight. It was still worth it!
Another one that I have some vague memories of is my very first comeback. I was still learning the game (my first MOBA) and it felt so cool that we managed to turn it around. I think that's when I fell in love with the game.