[Konctantin]

Какие есть? (режимы)

enum AuraRemoveMode
{
    AURA_REMOVE_BY_DEFAULT,
    AURA_REMOVE_BY_STACK,                                   // at replace by similar aura
    AURA_REMOVE_BY_CANCEL,
    AURA_REMOVE_BY_DISPEL,
    AURA_REMOVE_BY_DEATH,
    AURA_REMOVE_BY_DELETE,                                  // use for speedup and prevent unexpected effects at player logout/pet unsummon (must be used _only_ after save), delete.
};

вот тут прочитать можно кое что про "что делает", пройдитесь по коду, там вроде нормально прокомментировано:

void Unit::RemoveAura(AuraMap::iterator &i, AuraRemoveMode mode)
{
    Aura* Aur = i->second;
    SpellEntry const* AurSpellInfo = Aur->GetSpellProto();

    Aur->UnregisterSingleCastAura();

    // remove from list before mods removing (prevent cyclic calls, mods added before including to aura list - use reverse order)
    if (Aur->GetModifier()->m_auraname < TOTAL_AURAS)
    {
        m_modAuras[Aur->GetModifier()->m_auraname].remove(Aur);
    }

    // Set remove mode
    Aur->SetRemoveMode(mode);

    // if unit currently update aura list then make safe update iterator shift to next
    if (m_AurasUpdateIterator == i)
        ++m_AurasUpdateIterator;

    // some ShapeshiftBoosts at remove trigger removing other auras including parent Shapeshift aura
    // remove aura from list before to prevent deleting it before
    m_Auras.erase(i);

    // now aura removed from from list and can't be deleted by indirect call but can be referenced from callers

    // Statue unsummoned at aura remove
    Totem* statue = NULL;
    if(IsChanneledSpell(AurSpellInfo))
        if(Unit* caster = Aur->GetCaster())
            if(caster->GetTypeId()==TYPEID_UNIT && ((Creature*)caster)->isTotem() && ((Totem*)caster)->GetTotemType()==TOTEM_STATUE)
                statue = ((Totem*)caster);

    sLog.outDebug("Aura %u now is remove mode %d",Aur->GetModifier()->m_auraname, mode);
    if (mode != AURA_REMOVE_BY_DELETE)                      // not unapply if target will deleted
        Aur->ApplyModifier(false,true);

    if (Aur->_RemoveAura())
    {
        // last aura in stack removed
        if (mode != AURA_REMOVE_BY_DELETE && IsSpellLastAuraEffect(Aur->GetSpellProto(),Aur->GetEffIndex()))
            Aur->HandleSpellSpecificBoosts(false);
    }

    // If aura in use (removed from code that plan access to it data after return)
    // store it in aura list with delayed deletion
    if (Aur->IsInUse())
        m_deletedAuras.push_back(Aur);
    else
        delete Aur;

    if(statue)
        statue->UnSummon();

    // only way correctly remove all auras from list
    if( m_Auras.empty() )
        i = m_Auras.end();
    else
        i = m_Auras.begin();

}