Avernus Fried Chicken is a level 18 outsider that (very rarely) can appear as one of the summons available to a Hellfire Warlock via its second level feat Summon Baatezu. Its abilities and statistics are almost exactly the same as that of Koraboros, the most powerful Baatezu summons available by this feat. Conversation about its existence dates back to as early as 2009, being noticed both in this game and Baldur's Gate. Judging by the rarity of its summons frequency (about 1 in 100) and tongue-in-cheek game description, this foul fowl appears to be something of an easter egg:
Though outwardly it resembles a humble chicken - albeit engulfed in flames - sordid are the tales of the dreaded Avernus Fried Chicken. From the writings of the mad scholar Anvandyr in 1028 DR:
"Lo, and in the ages past, there lived on Toril great and terrifying birds, who rent flesh and snapped bone. When at last the final member died, Gargauth, God of Cruelty, took notice. Noted he the viciousness of the creature, and in appreciation he took up its soul and dragged it hither to the Nine Hells.
"Lo! Hearken and I fear! So did the Tenth Lord of Nine - with darkest rites and ancient incantations, use a horrifying mix of eleven cursed herbs and demonic spices to clothe the soul of the beast in a humble frame, forever wreathed in the flames of the Hells! For eternity, until Ao extinguishes the Sun, shall the dread Avernus Fried Chicken peck about at the feet of its master, its dark god! Forever shall the fumes rising from its twisted body tantalize and charm its prey, until its hellish form is upon them, rending their flesh with its talons and charring their eyes in their sockets!
"Quake at this revelation... and shudder that the Lost Lord of the Pit may send such a beast to you - that you may hear its hideous squawk tear through the nigh!"
Aged and ancient in realms of forgotten infernal lore, with an armor class of 45, 306 hit points, a base attack bonus of 18, regeneration, damage reduction, the create undead ability and spell resistance of 32, one thing for certain can be said of Avernus: he's a tough old bird.
Avernus is a reference to the first layer of the Nine Hells of Baator. It is mentioned in Baldur's Gateand (in the real world) is an ancient name for a volcanic crater near Cumae (Cuma), Italy, in the Region of Campania west of Naples.
Unlike most other summons from use of this feat, Avernus will always drop some sort of useful random loot in the Original Campaign (e.g. a scroll of Dominate Monster or a silver necklace). In this way, it is possible to earn some extra items. Although, in consideration of how often he appears, this may take some time. In addition, Avernus' loot is determined upon his defeat rather than the normal method of loot generation, when a foe is first spawned by the game.