Chimera shot

Hi. I found that on Blackrock shaman's http://wotlk.openwow.com/spell=16237 and priest's buff from http://wotlk.openwow.com/spell=15363 (http://wotlk.openwow.com/spell=15359) redusing chimera shot damage (http://wotlk.openwow.com/spell=53209) (nature damage) on 10% as well as aimed and other phisical damage abilities. Its pretty easy to test with "DrDamager" addon. With these buffs chimera almost always doing less damage then the possible minimum to the target withour resiliens and nature resist. Without buffs damage is always correct to addon.
Is this a bug or b patch thing? Or maybe its strange wotlk mechanichs? Cant tets this on other realms, only on blackrock, cos of client language, so asking here.