Ideas for DM's the Good, the Bad, the Trollish.

[Reaper34]

creature/villain with "what's mine is your's ability" - baddie takes all the hp damage but the pain of the attacks is felt by the target of the ability. target takes no accual damage but may have to make a death saving throw if baddie takes over x damage.

random treasure. 1d6 sling stones. one of the stones is accualy a philispher's stone with disguise magic cast on it. enjoy look of horror when player uses it as a sling stone and it cracks on baddies face splattering it with silvery liquid.

[RickAllison]

Bring back a defeated (but unkilled) villain from earlier in the campaign; make him strike an alliance with the party and watch as the paranoia rises to see who tries to kill him first.