Again, I 100% understand what you're looking for here, I just don't understand why it could work. You'd probably have to lower the damage to have an additional debuff (disregarding the thematic problems of like...fire blasts having toxic damage somehow), and...it's a sentinel. So. No.
It's too many toggles to track on top of 3-9 you're running already, you already get a variety of debuffs/secondary effect choices in the selection of a primary power set, and it makes an already less-than-appealing AT even less appealing.
I wish I had better for you, you obviously put some thought into this.