Is negate a game term in Riftbound?
Other card games use "negate." Is negate a game term in Riftbound?

[Hidden] (Hide now for to react with later for
.)
[Action] (Play on your turn or in showdowns.)
[Stun] a unit. (It doesn't deal combat damage this turn.)
If you played this from your hand, draw 1.
Artist: Caravan Studio
Card Set: Unleashed
Other card games use "negate." Is negate a game term in Riftbound?
I have Scuttle Crab on a battlefield and Back Off hidden. My opponent Smite kills Scuttle Crab. On the Deathknell, can I reveal Back Off and target a unit in base or elsewhere, or is it trashed because Hidden limits targeting to that battlefield?
I hide Back Off on one battlefield. During a showdown at a different battlefield, can I reveal and play it there?
Back Off can stun a unit and may draw a card if played from hand. If I play Back Off from hidden during a showdown, does the stun happen when revealed, and is the draw conditional on playing from hand?
I have a unit with Deathknell at a battlefield. In response to its Deathknell trigger I play Back Off and stun the enemy unit. My opponent then reacts with Vex, Apathetic moving into that battlefield. Does my opponent still get a conquer, or does Vex start a new combat before control is established? Do attacker and defender roles stay with the players until control is established?