Silliest tactics?

[The Larch]

When faced with evil abominations from the nether-planes I tend to use a most cunning device known as a "door." Many evil beasties have been cunningly foiled in this manner, for when guarding a fearsome magic item simply rushing past them, then pelting it back down the corridor and slamming the door before they can gurgle "ugh?" appears to completely fox such powerful creatures as beholders and conjured demons from hell.
Other less successful patented tactics of mine include rushing up to summoned demons and proceeding to biff them in a gentlemanly bout of fisticuffs until they go away.

[Prophet]

Hmmm, the door factor is the only black spot on the other wise improved monster AI. At least they've fixed the 'stand just beyond visual range and lob fireballs tactic'

To be fair to Beholders it must be damn tricky working a door handle with an eyestalk. Of course it wouldn't be a problem if they still had their disintegration rays :E

[Mori]

Similar to the fireball idea is a special Bounty Hunter trick I've used many a time. Simply lob a handful of caltrops (read: set a special snare) in the direction of a group of enemies beyond visual range, then hide in shadows before it goes off. With no-one to target, they make ugly hissing noises and then settle down in the same spot to lick their wounds. Repeat as often as required, but remember this won't work on creatures that can detect invisibility...