There's a mission that is recommended for (I think) level 14s which'll make that look like a cakewalk! Tried it as a level 11 with a level 9 and two similar levels via matchmaking and it was horrendous. Did it in the end but there was one bit in particular that was a nightmare.
Have to extract something, gives you five mins to clear enemies and extract stuff. The enemies are a crapload of cleaners and there are snipers that one/two shot you. All of this takes place in an arena that's a flaming inferno.
Jesus H Christ!