It's actually easier to solo Crazy. There is a vid on youtube showing the map and tactics.
When you play with more people the enemies just get harder.
Serious? I'll google it a bit. Would like to get that out of the way before concentrating on the last few MP challenges/trophies. Really enjoying the game now again that I don't have lag.
Edit : Here is one I found
Last edited by Nemesis; 18-02-2015 at 08:47 AM.
Reason: added link