Calling Monster Aficionados!!!

[Qwillion]

i recomend just a template the Force creature template (advanced bestiary, by green ronnin), along with any magical beast, monstrous huminoid, outsider or dragon.

 

[Thurbane]

How about a Will-O-Wisp with the Shadow Creature template (LoM, p167). Bumps it up to CR8, and gives it abilities like Fast Healing 2 and Mirror Image 1/day.

 

[Jhaelen]

How about a Will-O-Wisp with the Shadow Creature template (LoM, p167). Bumps it up to CR8, and gives it abilities like Fast Healing 2 and Mirror Image 1/day.

I've used the Phrenic template (from XPH) on will-o-wisps to great effect. My players absolutely hated that encounter. It made for a pretty extended combat.

They work best if you add some other (preferably heavy-hitting) critters when you use them, like ... a gray render, chuul or even a shambling mound