Play tag with the invulnerable Mudpuppy!
EDIT: Maintenance happened, this is all invalid now prolly. But word seems to be this randomly happens all over?
Extra edit: Passing by, the Mudpuppy seems to still be going at it. The Ice Sprite has buggered off, though.
Ok, weird random thread, and this probably won't be valid after maintenance in a couple days, but until then, might remain active.
Coerthas Central Highlands (17, 31), at the river from Mor Dhona heading to North Shroud, there's a Mudpuppy and an Ice Sprite just running in circles forever. At first, I didn't want to mess with them and break whatever weirdness was going on, but when I tried putting them to Sleep, I discovered they're immune to everything. Evidently trying to reset to a position they can't reach, far as I can tell. Current theory is they bugged out when a GM banned a bot underground that they were trying to target.
Whatever the case, nothing seems to be able to stop these two, so I say join the parade.