sometimes tag lasts even 1 round only, but i still don't understand what makes tag disappear when this happens.

anyways, to do some punctualizations for what i understood about these matters:

1) Tag reduces 30% of the enemy defense/resistance, does not increase by 30% the damage. It means, if you own 10000 resistance and 8000 defense (is just an example) then, as long as you are tagged, you'll be considered like if you had 7000 resistance and 5600 defense. So the damage increase is the difference between how much the first values reduce it and how much the second ones do.

2) Sleep, Immobile and Chaos replace one another, so, if you are chaosed and you get sleeped you are now only sleeped and not both sleeped and chaosed.

i'm pretty sure is capped at 95%