Ecology of the Dupli-cat (Coeurl)

Coeurl, Final Fantasy X

Nomenclature: black destroyer, coeurl, displacer cat, dupli-cat, greymalkin, missing lynx, pard, phase panther, phase tiger, shadow stalker, tangtal.

Description: a feline predator that exists slightly out of phase with reality, thereby concealing its position and evading attacks.

The coeurl (pronounced like "quarrel", I guess) originally appeared in the scifi novel Voyage of the Space Beagle as a monster of the week. Later, Wizards of the Coast claimed it as their intellectual property despite having absolutely no right to and Paizo had the gall to ask the Vogt estate for permission to use the monster's likeness in one of their adventures (Bravo!). Meanwhile, the Final Fantasy series has been using the coeurl as one of its monsters for years without legal troubles. I adore the Final Fantasy designs most of all.

The example in the monster manual, despite its long history, is just one variant of the dupli-cat (and is not permissible for third party publishers to mention). There are many varieties with concealment that replicate illusion spells such as blur, displacement, mirror image and/or invisibility, hence the punny nicknames. They are prone to mutation: some varieties have four, six or more limbs; others have tentacles sprouting from their muzzles or ankles; others have scaly legs and talons like birds. Because they are out of phase, most varieties display evasion similar to the rogue class feature as well as a "dimensional lunge" attack. This attack changes their position in space for a split second, long enough to lunge at targets otherwise out of reach, before snapping back in place.

A pseudo-naturalistic explanation of dupli-cats may be read at reddit. Since dupli-cats are monstrosities, I prefer an unnatural explanation: dupli-cats are one of the many bizarre fauna that wander out of the chaos wastes, possibly refugees from another plane. They are presumed capable of crossbreeding with big cats like panthers and tigers, which may be the origin of their many varieties. Dupli-cats commonly prowl the preternatural planes to prey on blink beasts such as blink dogs and blink bunnies. Some talented handlers among the Drow and the Unseelie Court have managed to train dupli-cats as hunting companions.

Sources: Adventures Dark & Deep Bestiary, Classic Fantasy: Dungeoneering Rules for Percentile Roleplaying, Forgotten Foes, The Genius Guide To: Simple Monster Templates, The Iconic Bestiary: Classics of Fantasy, Into the Green, Labyrinth Lord: Revised Edition, Tome of Horrors II.

ADDENDUM 6/21/2017: The coeurl's type depends on what place it has in the setting. If it's a natural part of the fantasy ecology, then it is a beast. If it's an unnatural thing which cannot reproduce itself, then its a monstrosity. If it's an alien bone vampire that subsists entirely on "id", as in the novel, then it's an aberration. Paizo's The End of Eternity gives them additional capabilities like echolocation, corroding metal with a touch, and producing vibrations to pick locks, disrupt machinery and shatter objects.

ADDENDUM 10/24/2017: A relative of the dupli-cat is the "space beagle" (see Octavirate Presents: Lethal Lexicon Vol 2). The space beagle originates from another galaxy, and escaped into to fantasy land from a crashed space ship. They display an irrational hatred of griffons.