In combat if both sides do not deal enough damage to kill all the opponents on one side, how does combat/damage resolve and who gets priority?

In a combat showdown, combat damage is dealt simultaneously, and the game proceeds to the Resolution Step once both players pass priority consecutively with an empty chain.

Here is the breakdown of how this resolves and how priority works:

1. Damage Assignment and Resolution

According to Rule 460.2.c and FAQ #1077, damage is not dealt until both players have finished assigning their total might to the opponent's units.

• Assignment: The attacker assigns their total might to the defender's units first, then the defender assigns their total might to the attacker's units.
• Dealing: Once all assignments are locked in, all damage is dealt simultaneously (Rule 460.2.c.1.a).
• Survival: If units remain on both sides after damage is dealt, they stay on the battlefield. Combat does not end simply because units survived; it continues until the Resolution Step.

2. The Resolution Step

After damage is dealt, the game proceeds to the Resolution Step (Rule 461). This step follows a specific sequence:

1. Combat Cleanup: All units are healed, and attacking units are recalled to their controller's base if defenders are still present (Rule 461.1.a).
2. Determine Combat Result:
   • If units from only one player remain, that player wins.
   • If units from both players remain (or neither player has units), the result is "No Result" (Rule 461.3.d).
   • Crucially: If "No Result" is reached and both players still have units at the battlefield, a new combat is staged at that location (Rule 461.3.d.1).

3. Priority and Focus

Priority during a showdown is governed by the state of the chain and the "Focus" designation:

• During the Showdown: As long as the chain is empty, players alternate having "Focus." The player with Focus has the priority to start a new chain. If a player adds an item to the chain, the state becomes "Closed," and players alternate adding reactions until both pass.
• After Damage: Damage assignment and dealing occur as part of the combat resolution process, not as items on the chain. Once damage is dealt, the chain is empty, and the players continue to alternate priority/focus to play further actions or reactions until both pass consecutively.
• Combat Ends: Combat only ends when both players pass priority consecutively while the chain is empty, leading to the Resolution Step described above.

Summary: If units survive on both sides, the combat will conclude with "No Result" during the Resolution Step, and a new combat will be staged at that battlefield. Priority throughout this process is managed by the alternating Focus system; you and your opponent will continue to have opportunities to play cards until you both pass consecutively.