Can you assign negative damage to units that cannot be dealt damage (like Kayn) during combat damage assignment?

Ruling: By the rules as written, there is no explicit restriction preventing negative damage assignment during combat. The rules only specify that valid damage must be a positive integer when dealing damage, but assigning damage is not the same as dealing damage, creating a technical loophole.

Nuances:

• Units that cannot be dealt damage (like Kayn after moving twice) are ignored for purposes of assigning lethal damage, but can still be assigned damage
• The rules state that valid damage is a positive integer greater than or equal to 1, but this applies to dealing damage, not assigning damage
• This is clearly unintended behavior and was recommended for rules feedback to clarify that damage assignments must be positive integers