Mirth -- a few that jump to mind, albeit not all semi-finals
Fuck Barca ties
Roma 3-0 second leg comeback vs Barca (quarterfinals)
Liverpool 4-0 second leg comeback vs Barca (semi's)
But the comebacks don't do hit quite like this where both teams have been top top quality for both games.
Pure drama ties
Dortmund vs Atletico in 2024 ending 5–4
Madrid comebacks vs Man City last two years
Chelsea/Liverpool back in 2009
Ajax/Tottenham
Chelsea/Barca with the Drogba eyes