Social Justice Chimera
It's pretty rare for PCs, aside from high-level Warlocks who want to have it always.How common is true sight though?
The spell True Seeing, which is the only way I know to get it is the spell("true seeing") which is a 6th level and lasts for an hour. Useful in combat, if you suspect an illusion, but if you don't?
But high-tier Demons and Devils have it, as do Sphinxes, Liches, and similar high-end monsters, and when that happens, it's always on and can't be dispelled or whatever.