Ive found the best place for the warrior is at the far end of the map under the arch. Lava isn't an issue and can usually get him nailed in a few minutes. Oddly though I find terramorphous pretty much impossible, never managed to kill him.
Easily my most played game to date. Run through it quite a few times with Zer0, Salvador and Maya. Currently on a second play through with Maya at level 49.
The DLC is fun too for a few extra hours, although its only recently that I played the Dragon Keep DLC.
Not playing it at the moment though, steam wouldn't open it for some reason.