[William]

Least fun: As the characters were digging through the already picked-over leavings in a shard of the abandoned Principality of Mariel, Demon Princess of Oblivion, one character picked up a scarf that shorted on him. The half-finished relic of the Song of Forgetting temporarily made him an unimportant stranger to everyone around him.

This was neat for about a hot second until we all realized that it was putting a severe crimp in the group's gaming rhythm. In Nomine is pretty heavy on coercive mental effects on the demonic side, and the players rolled with it and even took advantage of it (it's pretty easy to go raid the NPC's stash when they forget you're there), but it was definitely a jarring imposition.

Hardest to use: a D&D magic item made by a wild-spirited eladrin child, so it was meant to be a bit odd. You could speak the language stored in the ring. You could also switch out the language with one you knew, gaining permanent understanding of the language in the ring and forgetting the one you charged it with, other than by using the ring.

A weird and difficult magic item to make -- few casters are willing to drop a hard-earned skill point into equipment -- but meant to inspire teamwork and strategizing, passing it around and manipulating it as necessary. The simplest use, of course, is just to give it to a party in need of a new language from an external source, and this is what happened.