Any fight sequence that is prolonged beyond the realms of believability just to make for a bigger audience thrills.
I'm looking at YOU in particular Marvel films.
OK I know its supposed to be sci-fi and fantasy but character X, meets baddie character Y (whose is supposedly infinitely more powerful then their counterpart). X is getting expectedly battered by Y but then all of a sudden K,L,M, N and O come in from nowhere and despite they and X each being inferior to Y, together they make a decent shout of battering Y for a bit.
Sadly though X hits a bit of bad luck and gets killed. Now Y is able to steal all of X's powers and become even stronger. It looks like the others are on a hiding to nowhere.
Just as all seems lost, it suddenly transpires that X wasn't dead after all (despite the manner of their earlier death being in a way that we are all told is THE ULTIMATE DEATH FROM WHICH THERE IS NO RETURN POSSIBLE). Even though Y has all his powers, X is now for some unfathomable reason more than a match for Y and without the help of anyone else defeats Y once and for all.......until the next movie when more basic physics are reworked and Y is back on the scene again.