3-Headed Zombie Hydra Location?

[E]

Just as the title says, I'm looking for where the little turd is for achievement purposes.
Is it the same one guarding the earth orb? If yes, how'd you get 3 heads instead of the 2 that just spawn on the encounter?
I've tried killing 1 head to try spawning another but only 1 head spawns. Do I need more patience for it to spawn another head while fighting? If not, does it respawn though(after getting the earth orb cause i havent checked yet)?

[Meneluma]

Just try to go to the area to fight the final boss, you'll find a couple off missing bosses there the three headed hydra included.

[E]

Originally posted by Wishmaker_Latias:

Just try to go to the area to fight the final boss, you'll find a couple off missing bosses there the three headed hydra included.

Oh. never occured to me that It'd be there. I've been cleaning out all areas and dungeons before the Ultimate Chibi Knight battle. Thanks.

[Silly Pigeon]

next screen after ultimate chibi is suppose to be the 3 headed zombie boss
if u kill it on lower difficult, u will need to fight it in the temple of trials mid boss marathon