Two-Headed Zylork (POTN)

Phantom of the Nightmare
A Zylork, along with two Helmatrops, appeared through a portal in Hayley's nightmare while the latter was under the influence of a Dreamworm.

The Zylork and the Helmatrops restrained Ace, Gwen and Mark, but shortly after disappeared when Hayley's nightmare shited to another location.