Rakshasas

Rakshasa are actually fey from an area in Arcadia that mimics the hells. Despite it being, in fact, faeries, they act and look like fiends. They are evil-aligned outsiders, but effects that detect or specifically affect fiends do not affect them.

In Arcadia illusion magic is treated as, mostly, real. Creatures that fail their saving throws against illusions treat the effects as real, including taking damage from them. Creatures that make their saves are unaffected. Damage, generally, is 1d6 per level of the illusion effect used to create it, or 1d6 per 2 HD of the creating creature.

Alternatively, if it mimics an existing spell's effect, treat it as half damage. So, a fey soldier creating a glamer of a forest fire with a Mirage Arcane would mimic a fireball of 7th level, or a 12d6 fireball. Half damage means 6d6 of actual damage, but it's save-or-none rather than save-for-half. Healing, similarly, is halved.

Fey, outside of Arcadia, are affected by illusions in the same way as if they were in Arcadia. Their illusions, conversely, do not affect other creatures outside Arcadia except as illusions. The fey are not confused by this effect; they recognize that it's simply their nature. Fey killed outside of Arcadia simply vanish, reappearing in Arcadia and potentially coming back.