Your favourite boss when doing jolly cooperation.

Couple of ones for me.
O&S like everyoneelse. I like to put the smack down on those 2 in revenge.
Nito is fun if you have a smart host who doesn't run off and take him on straight away. If they wait at the beginning its great.
Seath as well, especially if you can get them the MLGS.
And finally a surprise one, one no one has mentioned yet :suspect:

Spoiler:

:affraid: Haha thast right. When Chi and I did our co-op playthrough we both needed a certain spell so we went and killed them and its real fun. He was an archer I was melee and we worked on timing our runs and getting some hits. Its a great fight to co-op.