yeah yogsloth, I just beat Diablo at level 32. Use potions...
On a related note, something should unlock when you defeat Diablo, because currently there's no reason to continue.
Easiest way to get the card: Fast forward to 4th level (right-click -> forward, several times) then collect all the weapons and use the smg. Just constantly fire at the container, you'll kill most of the enemies as they come out. Once you get more than 3333 pts, die and do it again. Rinse, reapeat.
Here's what I really hate. Sitting there in the lobby waiting for my match to start, takes too long so I hit "leave" then it goes to game and I lose automatically. So frustrating!
Three clerics up front. One concentrates on endurance and healing (1 pt endurance, 2 pts intellect each turn). The other 2 beef up end. and strength. In the back, an archer. You will never die with this set up.
Kerbouchard: If your cleric has some points in benediction, just keep using heal, (not heal all) and eventually it'll get removed (depending on how many points you have in benediction).