Rupture is applied before attack damage is calculated

[Iridar]

Relevant code

It's not perfectly clear if this is a bug or intended behavior, since only the Rupture ability uses the rupture mechanic. The ability description implies the Rupture Shot itself shouldn't benefit from this bonus damage.

A Rupture shot deals critical damage and ensures that the target takes an additional +3 damage from all attacks in the future.

For comparison, nor Shredder nor Holo Target provide any benefit to attacks that apply them. It would make sense for Rupture to behave the same.

[Iridar]

Discord recap. In this context:

• rupture (lowercase) is the mechanic of attacks applying a rupture value to the target, increasing the damage it takes from the following attacks by that value.
• Rupture (capitalized) - the Grenadier's ability, the only vanilla ability that applies rupture.

There are three explicit issues with rupture:

1. Maximum amount of bonus damage rupture can add to an attack is capped by that attack's damage, meaning that rupture cannot provide more than +100% bonus damage. E.g. if the target is ruptured for +3 and you use an attack that deals 1 damage, it will receive only +1 bonus damage from rupture.
2. If an attack applies rupture, the attack itself will be able to benefit from rupture. E.g. beam Cannon deals 8-10 +3 damage, so 11-13 on a crit, but with Rupture ability it will hit for 14-16, with extra +3 coming from rupture applied by Rupture itself.
3. Rupture doesn't stack, highest value is used. So if you use Rupture on the same target multiple times, it will still be ruptured only for +3.

The Rupture's ability description is as follows:

A Rupture shot deals critical damage and ensures that the target takes an additional +3 damage from all attacks in the future.

And I think the description should take precedence over established mechanics, because that's how the player will expect the ability to work.

From the description, issues (1) and (2) are clearly bugs, and go against how the player will expect the ability to work. Therefore I declare them as bugs and move they be fixed with extreme prejudice.

Issue (3) is open to interpretation, as both rupture stacking and not stacking would make total sense with the current ability description. Therefore I suggest we don't do anything about it. If a mod needs to apply stacking rupture, it can be easily done with a custom effect that does TargetDamageable.AddRupturedValue(TargetDamageable.GetRupturedValue() + X);