It’s our first sahkil! A new category of outsiders introduced in Bestiary 5, sahkils are renegade psychopomps. All too aware of the mortality of all things, they would rather spend their finite eons making souls suffer rather than shepherding them. Taking forms out of nightmares—nightmares that even death is no release from—they find inventive ways to spread terror and torment living victims and vulnerable souls.
The esipil may be the weakest sahkil revealed so far, but they’re also my favorite. They’re just so gleefully malevolent, particularly given their habit of masquerading as lovable pets that are seized by sudden violent outbursts. (I once dogsat a racist Dachshund, so I can confirm that that sudden transformation is scary as hell…not to mention humiliating to all parties involved.)
And the best part about them is that they can be familiars! I so want to see one of these in a Hogwarts/Glantri School of Magic-style campaign, or in a guild or society (such as the Pathfinder Society) where members of different alignments are forced to coexist and play nice. Imagine a group of students sharing their classrooms and corridors with students and familiars of all shapes and sizes…but one of the familiars (ideally that of a hated rival or resented professor) is just wrong somehow. This feeling might persist for days, weeks, or even whole semesters until the esipil finds the proper moment to reveal itself in the way that causes the most fear.
Adventurers traveling to the Ethereal Plane are greeted by a talking terrier who claims to be a party member’s spirit guide. The mutt is helpful in all things until he is able to catch the character alone or in combat with other ethereal threats. Then the terrier, actually an esipil, uses cause fear and then attacks, howling to summon the rest of his pack.
Ever since a young wizard’s near-death from drowning, an immature nosoi has been his companion (due to become an ordinary nosoi when the wizard achieves the appropriate level and feat). Having such an exotic familiar at such a young age has earned him no small praise from his masters and peers at the Academy…save for one lecturer, who seems to dislike the birdlike psychopomp intensely. The lecturer’s familiar is actually a carefully disguised esipil, and the beast spends every night whispering dreams of torturing the nosoi into his master’s ear.
Cast off by their outsider masters long ago, a doru and a esipil haunt the souk in Ibor. When the esipil successfully cajoles his way into the service of a haruspex, the doru becomes mad with envy. The resentful div finds down-on-their-luck adventurers and offers to show them the graveyard where the esipil has stashed his treasure. Should the esipil discover he has been robbed, he will do everything in his—and his soothsayer master’s—power to exact revenge.
—Pathfinder Bestiary 5 213