Three reasons to clean up after yourself

    Most character parties don't leave much behind after a successful dungeon expedition: A few copper pieces and lots of dead monsters, but not much to give themselves away. But for the wily necromancer intent on vengeance against the intruders who stole his treasure and killed his minions, there's plenty.
    Battles leave behind blood. Magical healing repairs damage and blood loss, but the blood's still there: on walls, floors, and in the mouths and bellies of thirsty beasties. Not much to worry in the good old Dark Ages before DNA evidence (though wizards seem to have developed cloning already, and mass charm or feeblemind would explain the O.J. Simpson verdict), unless your enemies are into voodoo.
    Vengeful necromancers can usually find enough hair and tissue samples under the fingernails of their minions. But sampling can be more subtle. That temptress at the tavern wasn't after the thief's coin purse after all; she was after a few hairs. It seemed such an unusual request to her from that strange old gentlemen across town, but the money was too good to question it.
    The inclusion of these new threats will inject a little paranoia into one of the last few areas players haven't obsessed about already: personal grooming and hygiene. Before long, the party will be burning their nail clippings, wearing hairnets, and delegating all barber duties to the cleric. (Well, it least they're not restricted to blunt instruments anymore. Ow. Ow.)
    Perhaps now cavaliers won't be so casual about giving a lock of hair to the next admirer who comes along.

Bloodhound of Sicierus

Fear stalker

Voodoo doll golem