What am I expected to tank?

[Pyrion]

As others have said already, the skeletal monk is a beast. Strategy should be to go all out on it so it dies very very fast. Maybe even the cleric should undead nuke. Dont know how good is the damage potential of your group. You could even try to root/nuke it as it does not have unusual HP for its level, just dishes out a lot of damage. Stuns maybe helpfull as well (and slows obviously).