If there is a ready unit defending Reavers Row and they choose to use Reavers Row trigger, does it move back to base ready or exhausted?

If a ready unit is defending at Reaver's Row and you choose to use the Reaver's Row triggered ability to move it to your base, the unit remains ready.

According to the RiftJudge FAQ #3150:

"The unit remains ready. Reaver Row and other move effects don't change the orientation of a unit unless explicitly stated. Only the Standard Move action has exhausting as a cost."

Why this happens:

1. Movement vs. Standard Move: The only move action that requires exhausting a unit as a cost is the "Standard Move" (Rule 143.2).
2. Ability Effects: When an ability (like the one on Reaver's Row) instructs you to move a unit, it simply changes the unit's location. It does not impose the costs or state changes associated with a Standard Move.
3. State Preservation: Unless a card specifically says "exhaust the unit" or "the unit enters exhausted," the unit retains its current orientation (ready or exhausted) when it is moved by an ability.

Summary of the sequence:

• The unit is ready at the battlefield.
• The Reaver's Row trigger resolves.
• You choose to move the unit to your base.
• The unit arrives at your base in its current state: Ready.