How to beat the last level?

You will needed rocket raccoon lvl max,groot max,Angela max,star lord max first nebula comes use groot power combo with raccoon then tap star lord tap the fire blue shot nebula use star lord power health ship supplies and shield use Angela last power to all enemies and then use all power groot I believe after nebula dies who is survived are Angela or star lord for me I would like star lord and Angela I do like too but she power really slow to reload.star lord trick the last boss run and deflect from his attack and release fire blue then drop supplies that time is your chance to kill him Angela trick and use fire red then use first power.yeah and actually boss has 10 or 5 life to revive yeah kinda shitty boss so be careful.no problem
-Mohd Haikal Al-Amin Malaysia

This is the hardest level in the game, much harder than previous ones. The problem is that, up to this point, you can get by with high-offense characters along with healing. That strategy fails spectacularly on the last level; I came in with max-level Star-Lord, Gamora, Drax, and Mantis, and all of them but Mantis were one-shot kills in the first five seconds.

After a good deal of trial and error, I discovered that the enemies of this level deal large amounts of either physical or energy damage, so characters with high defense in those areas is a must. The Hulk and Vance Astro have equipment with strong physical defense modifiers, as does Mantis. Those three should form the core of your team, and all need buff items that add to their energy resistance. ISO-8 by itself isn't enough; you need energy resistance... Otherwise, the ISO will buff your physical resistance but still leave you exposed to the energy attacks.

You can experiment with who you want for a fourth character: I tried several and all of them died (contrary to what the bio says, Charlie doesn't strike me as much of a tank), but the good news is that you can survive this encounter with just three. In fact, the first time I succeeded, it was with Hulk (who is now officially my hero) with Mantis doing auto-heal, and before that I almost got away with it with just Hulk after Mantis went down. The second time I succeeded, it was with Vance Astro + Hulk with Mantis healing both, and it was a pretty swift victory.

Attack-wise, you'll make your life easier by using Hulk and Vance's daze / knockdown attacks: Hulk's foot stomp and hand clap, Vance's seeing stars and synapse snap. Let your melee's pound continuously with these attacks and keep them close together so Mantis can do her thing (make sure Mantis heals constantly and the auto-heal has it's radius skill on), and you should come out on top.