How does combat damage distribute when attacking with multiple units and they are defending with multiple units?

When multiple units are attacking and defending, combat damage is resolved through a two-part process: Assignment (which is sequential) followed by Dealing (which is simultaneous).

According to Rule 443.1 and the associated FAQs, here is the sequence for resolving combat damage:

1. Sum Might: Each player calculates the total Might of all their units currently in combat at that battlefield.
2. Assign Damage: Starting with the Attacker, each player assigns their total Might as damage to the opposing units.
   • Sequential Assignment: You must assign lethal damage (damage equal to or exceeding a unit's Might) to one unit in full before you can assign any damage to the next unit (Rule 443.1.d.3).
   • Tank Priority: If any units have the Tank keyword, they must be assigned lethal damage before any units without Tank (Rule 741.1.b).
   • Assignment vs. Dealing: Assigning damage is not the same as dealing it. You are simply declaring how the total damage will be distributed (Rule 443.1.d.1).
3. Deal Damage: Once all damage has been assigned, it is dealt simultaneously to all targeted units (Rule 443.1.d.1.a).
4. Cleanup: Units with damage marked equal to or greater than their Might are killed.

Important Nuances:

• No Excess Assignment: You cannot assign more damage to a unit than the minimum required to reach lethal, unless no other units remain to receive damage (Rule 443.1.d.4).
• Simultaneous Dealing: While the assignment process is sequential to ensure lethal damage is distributed correctly, the actual dealing of that damage happens all at once.
• Stunned Units: Stunned units contribute 0 Might to their side's total and are still eligible to be assigned damage.