Some tweaking I think this is a better build:
Motherless Tiefling race (+1 bite)
Close to the Abyss mythic ability (+1 gore)
Mutation Warrior 9: Feral Mutagen (+1 bite), Weapon Training for two weapon types (Natural + any weapon), Feral Wings
Sohei 1: (+1 attack from Flurry)
Stigmatized Witch 1: Iceplant hex & Lizard familiar (+5 AC with ring), Wolf-Scarred Face (+3 bites)
Bloodrager 1: Serpentine bloodline (+1 bite)
Crossblooded 1: Serpentine bloodline (+1 bite), Draconic bloodline (access to DD)
Dragon Disciple 2: Dragon bite (+1 bite), +2 STR, +1 AC
Instinctual Warrior 4: WIS-to-AC, Uncanny Dodge (I wonder if Demonic Rage turns on both rages?), Animal Fury rage power (+1 bite)
Demonslayer 1: FE - Evil Outsiders
TWF Daggers: 4 attacks (BAB 16) + 5 offhand attacks (Hasty Eradicator)
Haste (+1 attack)
Extra Rage Power: Lesser Fiend Totem (+1 gore)
Total: 22 attacks per round
Now I just need to figure out how to tag something nasty onto these attacks to make them actually hurt...