After finishing each of the week's challenges, there's a secret star on the odd numbered weeks (and a Banner on the evens) that you can find that's like...a full level i think?
I was thinking what would be a lot better in a game mode is an "Avenge the Fallen" LTM; one player manages to get the infinity gauntlet (or even...an AI controlled Thanos?) who starts attacking a group of 50/100 players. Throughout the map, there's each of the main 6 Avengers' weapons that you can get to fight Thanos (Stormbreaker, Cap's Shield, Iron Man gauntlets, maybe like Hawkeye's bow (basically a reskin of the boom bow), dual pistols/electric pistols for Widow and ...i dunno maybe like a super shield for Hulk?)
Sounds fun to me. The Hulk item can be Hulk hands that can destroy builds in one hit.