well...

there are Finn Edwards in a street whit his special mission completed (he can move with the moon and the sphere like a monster durng the monster's movemente phase), a Byakhee (O) in the sky and the portal for the Dreamlands () with the arrow special ability and it's adiacent to Finn... Mythos phase: movement is the in the white and the O in the blak... who move first?

exemple: the Byakhee (o) move to Finn because hi is in the street, but Finn (O) at the same time move to the near portal avoiding the byakhee because while Bhyakee was moving in the Finn's street he moved to the portal. But the portal () move too and it goes to the Finn's first street area (wher now there is the Byakhee)!

... ....mmm ...I think it's hard to understand

the forum can't read the slah symbol... the portal has the slash and move in the white

Generally speaking, I'd say there are no rules saying what moves first. Hence, the usual "First player" decides is the rule I'd follow

I agree with Julia.

I can't find anything written about this except that Finn moves like a normal monster.
I guess it's all supposed to happen at the same time. But that doesn't really work.
Normally things don't react to each other during the monster movement and there are no problem.

Another idea is that the player controlling Finn may choose when to move him and the first player decides the rest.