Marvel Super Hero Squad: The Infinity Gauntlet

Just need to beat the game in Challenging Difficulty. You will likely die a few more times than you did in the lower levels, but the checkpoints are very forgiving, so there's really not going to be a lot of frustration. Be vigilant about reviving your partner, especially during boss fights, as he/she can serve as a great decoy while you blast away at the boss from safety. Worked great for me on Thanos and the Dark Surfer.

Worth noting that the difficulty achievements are stackable, so if you beat the game on Challenging Difficulty, you'll also get Squad Member (for Normal difficulty) and Squad Initiate (for Easy difficulty).

I've played through the entire game on both Easy & Challenging, and honestly there's very little difference between the difficulty levels. You'll probably die a few more times on Challenging, but it's not that much different. Save yourself some time and just play through on Challenging.

Focus on reviving your buddy whenever you can (particularly during boss battles) and spam those ranged attacks when you can.

Achievement pops after beating the Dark Surfer n Level 11 with Iron Man & Black Widow.

If you get stuck on any level, the following playlist might help: https://www.youtube.com/playlist?list=PLrXlEm4MgsbPi0wqTeu8e...

Its on a lower difficulty I believe, but still will help with some of the puzzles in the game, or how to beat certain bosses, etc.