If they're going to be that smart then magic-using monsters should never cast poison on other magic-using monsters, since they'd realize that it'll be insta-cured anyway. I actually find it less ridiculous to watch them try to poison creatures immune to poison than the Poison/Cure/Rinse/Repeat festivals that happen every time two spellcasters fight.
I'm a few pages late, but why waste a good pvp dexer template with music/peacemake. in OSI, and many other freeshards it was always possible to farm for gold on a pure dexer. why change it?