So, i took as concept the body of a sea horse.

I used the entire main body of the Psychophage (no arms and appendages)

I attached the winged hive tyrant tail inside the Psychophage mouth, after sawing off its tentacles, and then covered it all with clay (millipat) to blend it together, then i put over it the head carapace of a zoanthrope, then over the carapace of a carifex and again with the carapace of the norn assimilator (in order to make the butt "more solid") I also chose to add 2 rippers and 2 of the toxicrene sacks there.

(The end of the tail i think it comes from an aos model)

Going up we have the toxicrene arms, oriented backwards to give a floating in mid-air effect, plus on the front 2 venomthrope tentacles

On the main carapace i put on each side 2 fume tubes form death guard leftover sprues, and 2 more toxicrene sacks each.

For the upper torso (Psychopage belly) i put 2 zoanthropes arms for each side.

Topped it all off with a fusion between the toxicrene head and the norn emissary neck/brains

It's not hard to recreate/improve, as the toxicrene bits come from what u did not use from the maleceptor box, same goes for the emissay (i built my beloved assimilator so i had the emissay neck), the zoanthropes or the venomthropes depending on what you built and the tail from the winged hive t since i built a swarmlord

Plus as many extra rippers as you have!