If I use Heedless Resurrection and kill my only unit at a battlefield to pay its cost, can I play the resurrected unit to that same battlefield?

Ruling: It depends on whether you are attacking or defending, and whether a showdown is ongoing.

Sequence:

• Targets are chosen before costs are paid, so you cannot resurrect the same unit you kill for the cost.
• If resurrecting a different unit from your trash, battlefield control determines where you can play it.

Nuances:

• On defense during a showdown: Yes, you can play the resurrected unit to that battlefield. You retain control because battlefield control cannot change during an ongoing showdown.
• Outside of a showdown (open play): Yes, you can play the resurrected unit to that battlefield. You only lose control of a battlefield when you have no units there AND the turn is in an open state. Since Heedless Resurrection creates a chain (closed state), you retain control throughout its resolution.
• On attack: No, you cannot play the resurrected unit to that battlefield. As the attacker, you do not control the contested battlefield and cannot play units there.