The ypotryll sports “the tusked head of a boar, humped body of a camel, legs and hooves of an ox or goat and tail of a serpent,” according to Wikipedia (though the Bestiary 4’s looks a bit more reptilian from the neck down). It’s also pretty much a blank slate, as it is an obscure creature from heraldry. So deploy it however you like. When your players are yawning at T. rexes and nightmares, a CR 15 structure-destroying ypotryll might be just what’s called for.
Evangelus Mumford’s coat of arms is emblazoned with an azure ypotryll—and he can’t claim his inheritance until he kills one. He plans to do no such thing and will handsomely reward anyone who can slay one for him. On a side note, researching the history of the blue charge on the Mumford coat of arms unlocks a secret about a weakness in Fang Citadel’s southern gatehouse.
Desert folk know that hippopotamuses are dangerous. So there is bemused excitement when the pharaoh fills the arena with water for a mock river battle in hippo-infested waters. But when it turns out the river battle is to be fought by slaves, giants, captive adventurers, and ypotrylls, the betting and doomsaying begin early.
The ratfolk are on strike. They’ve stopped trash collection and street sweeping, and refuse to go into the city dump under any circumstances. The reason is an immature (use the Young template) ypotryll that has taken up residence there, jealously killing anyone who intrudes on its new home. That explains the ratfolk’s fear but not their militancy—they blame forces on the Council for putting the demon-shoat there. And where are the ypotryll’s parents…?
—Pathfinder Bestiary 4 285
An obscure creature from heraldry, eh? At least it’s not the roving mauler.
And yup…adventure seed #2 features an ypodrome.
You know what sucks? Fevers you get from sharing the air with a planeful of people. But at least I got this entry up!