Ice devils should have a slowing attack, like they do in D&D. Most likely, this should be like a lichen’s temporary slow in EvilHack, rather than a permanent speed-loss like a shade or skeleton has. Free action could reduce or negate this.

Hellfire from monster casting, being inspired by Ghost Rider, should in addition to ignoring fire resistance slow the player down, since it does spiritual damage that reduces the victim’s will to act.

Dragon with slowing breath. The effect stacks with previous effects of slowing breath.