KMST 1.2.454 - Resistance Hyper Skills, November Update

For the Cannon Shooter discussion, the damage reduction is distinctly listed as the variable x, instead of a negative damR. I doubt this is a limitation where damR can't be negative, as that seems to be rather unnecessary. Despite Overburn showing in range, it should be like every other +damR% bonus, and stack additively with things like +Total Damage% potential and Boss Damage, identical to Demon Slayer's Concentration, and the like. A very recent example of this is Angelic Buster's Soul Contract. It gives +100% damage, and literally doubles your range. However, your damage cannot double because it adds 100% Total Damage, and Angelic Buster already has a ton of Total Damage that's added to their range. So at the most, it gives a 1.5x increase to damage output, even though it doubles the range displayed on your stat window.

That being said, I believe Cannon Shooter's Buckshot to affect skills like Phantom's Talent. The skill's base damage itself is reduced, not the Total Damage sum available. So if a skill does 500%, it now does 300%. Add Overburn, it will go to 420%.