Hello friends, it's been a while

I haven't been active on the forums, but I'm still an active RPG Maker. Anyways....
I'm using Tankentai's ATB battle system and the Notetags Add-on by Mr. Bubble. I'm using the <atb damage: -25%> tag to make a State that interrupts casting of one enemy.
Here's the problem: I want to be able to use it during bosses, but the player can easily win any boss battle without ever being hurt if they keep spamming the interrupt. I've been trying for at least an hour to find a solution, but I'm stumped. I've tried stuff like making a 'Just Stunned' state that resists the Interrupt and lasts for 2 turns after the interrupt...but that doesn't work. I guess because there's no way to resist a state with another state. I've tried all kinds of combinations of 'State to Cancel' and 'Offset by Opposition' stuff, but still nothing.
I'd greatly appreciate any help. Thanks in advance