I have 36 standard covers from the latest PVE event. My 1* roster is filled out, and I’m working on covers for my 2* and 3* heroes. What do you do with all those covers? Bust them, and sell the unnecessary 1*'s for ISO8 and hope to get some 2* covers in there?
Pretty much.
You’ll get alot of 1s, but may get a few 2s and if you are really lucky a 3*.
Whatever you don’t need, sell for ISO and use it to level your characters.
Thanks Alexraven! Out of 36 packs I got 8 2* covers, which seems like a good return. 2 
Thor, 
and 
Bullseye,
Magneto,
Moonstone,
Torchling,
Daken,
Moonstone
Glad I could help.
Winning matches can also get you some 2*s pretty regularly, so it pays to play at least the seed teams for every event including lightning rounds to up the chances of them dropping. Plus it gets you ISO.
Good luck building those 2*. Won’t be long before you have them covered pretty well.