TrinityCore/TrinityCore — pull request #12233 by Trisjdc (2014-06-07 22:27:21+00:00)
Title: Core/Auras: Expanding functionality of SPELL_GROUP_STACK_RULE_EXCLUSIVE_SAME_EFFECT to be able to take care of aura effects inside their handlers

Currently handled:
- SPELL_AURA_MOD_RESISTANCE_PCT
- SPELL_AURA_MOD_STAT
- SPELL_AURA_MELEE_SLOW
- SPELL_AURA_MOD_MELEE_HASTE
- SPELL_AURA_MOD_DAMAGE_PERCENT_DONE

Necessary to allow stack rules such as BoK/BoS/Bok-Drums and others to be all in a target with all of the aura effects, yet with only the 'highest' effect active

Needed for https://github.com/TrinityCore/TrinityCore/issues/4313