Can this only be used to stop an attacker if it was used in the attacking players Deployment phase?

The way the conflict windows read it looks like the active player could declare an objective, then all attackers, THEN player actions happen. So Force Stasis becomes useless. Unless it would "Remove" a unit as an attacker.

Can I get some help on timing this card?

There is an action window in the conflict phase where you get a chance to perform actions before the attacking player can engage an enemy objective. You would have to play it during this step, since Force Stasis would not remove an attacker if it has already been declared.

Declaring an engagement is not an action.

there is an action window before the active player can choose an objective to engage

there is an action window before the active player can choose an objective to engage

The way I read it, the action phase before the conflict phase is in the deployment phase.

Right from the rule book page 30

Deployment phase

Deploy phase begins

Player actions

Deploy phase ends

Conflict Phase

Conflict Begins

Player Actions --- side bar for how player actions work in this window.

--- Active player chooses one enemy objective to engage

--- Active player declares attackers

--- Player Actions

--- Opponent declare defenders

--- Player Actions

--- etc..etc..

Noting the player actions step in the conflict phase has a set process for the window, the only time you can play force stasis is after active player declares attackers. Or should the process be

Conflict phase begins

Player actions

DS plays Force Stasis

Player actions/responses

Declare objective

Declare attackers

Player action

Declare defenders

*edit*

OMG how did I miss that. Disregard. I just noticed the resolve engagement arrow bit that makes this make sense. For some reason I was reading the Player actions arrow as pointing towards the side bar, not returning to it.