Old flash animation

So when I was a kid I watched one flash animation that you could find on game sites and such... The animation was about famous characters fighting. It started with the band kiss rocking and idk but someone entered the building and killed them and it was just going on so... There was luffy, naruto, asterix, sparta etc... The ending scene was kratos fighting with galactus... There was also harry potter, it was just full of those famous characters like full of marvel characters and such.... Thanks for any help.