I've never encountered anything of the like, but I haven't played a majority of games on the market. It would certainly be interesting to design such a buff.
It would also be interesting to design one that had both helpful and harmful effects. Like, getting buffed to resist cold spells makes you more vulnerable to a fire spell, and it just so happens that one of the dreaded Icemen of the Tundra is tricky and has learned fire spells to use on his competitors.