If you move to an open Battlefront and opponent responds with an action spell like Void Seeker, will the move trigger happen?

Ruling: Yes, the move trigger happens upon arriving at the new location. Since the opponent is playing an action spell, you must already be in Showdown, meaning the trigger has already happened and fully resolved before they can respond.

Nuances:

• If a reaction was put on the chain in response to the move trigger that caused the unit with Eye to be killed or moved to hand (like Gust), then the move trigger would resolve to no effect since the source is now null.