When goats discover caves leaking Earth Blood, the mutagenic forces sometimes turn them into chaos beasts, growing lion heads, monstrous claws, dragon heads, snake tails, serpent tongues, and so on. These beasts are related to other multi-headed creatures like the hydra or the kerberos. They all like to guard entrances to the netherworld.
The goat head usually just yells curses and insults but the other heads will fight with its claws and lion bite, and a dragon bite or its dragon fire (3×/day): if you are in melee with the chimera, take 6d6 fire damage. Save vs. dragon breath for half damage.
HD 6 AC 5 1d6/1d6/1d10/2d10 or fire F6 MV 9 ML 10 XP 820
Treasure: Older chimeras will often have amassed quite some wealth, for they they do not only prey on those who wish to enter but also on those who wish to leave the netherworld. 50% for 1d8x1000 silver, 50% for 1d8×1000 gold, 20% for 1d6×100 platinum, 30% for 3d6 gems, 20% for 1d6 jewelry, 20% for a magic item.