bool Unit::isSpellCrit(Unit *pVictim, SpellEntry const *spellProto, SpellSchoolMask schoolMask, WeaponAttackType attackType)
{
    if (IS_CREATURE_GUID(GetGUID()))
        false;

    // not critting spell
    if ((spellProto->AttributesEx2 & SPELL_ATTR_EX2_CANT_CRIT))
        return false;

    for (int i=0;i<3;++i)
    {
        switch (spellProto->Effect[i])
        {
            // NPCs cannot crit with school damage spells
            case SPELL_EFFECT_SCHOOL_DAMAGE:
            {
                if (!GetCharmerOrOwnerPlayerOrPlayerItself())
                    return false;
                break;
            }
            // Leech spells are not considered as direct spell damage ( they cannot crit )
            case SPELL_EFFECT_HEALTH_LEECH:
                return false;
        }
    }

    float crit_chance = 0.0f;
    switch (spellProto->DmgClass)
    {
        case SPELL_DAMAGE_CLASS_NONE: // Exception for Earth Shield and Lifebloom Final Bloom
            if (spellProto->Id != 379 && spellProto->Id != 33778)
                return false;
        case SPELL_DAMAGE_CLASS_MAGIC:
        {
            if (GetTypeId() == TYPEID_PLAYER)
                crit_chance = GetFloatValue( PLAYER_SPELL_CRIT_PERCENTAGE1 + GetFirstSchoolInMask(schoolMask));
            else
            {
                crit_chance = m_baseSpellCritChance;
                crit_chance += GetTotalAuraModifierByMiscMask(SPELL_AURA_MOD_SPELL_CRIT_CHANCE_SCHOOL, schoolMask);
            }
            // taken
            if (pVictim && !IsPositiveSpell(spellProto->Id))
            {
                // Modify critical chance by victim SPELL_AURA_MOD_ATTACKER_SPELL_CRIT_CHANCE
                crit_chance += pVictim->GetTotalAuraModifierByMiscMask(SPELL_AURA_MOD_ATTACKER_SPELL_CRIT_CHANCE, schoolMask);
                // Modify critical chance by victim SPELL_AURA_MOD_ATTACKER_SPELL_AND_WEAPON_CRIT_CHANCE
                crit_chance += pVictim->GetTotalAuraModifier(SPELL_AURA_MOD_ATTACKER_SPELL_AND_WEAPON_CRIT_CHANCE);
                // Modify by player victim resilience
                if (pVictim->GetTypeId() == TYPEID_PLAYER)
                    crit_chance -= ((Player*)pVictim)->GetRatingBonusValue(CR_CRIT_TAKEN_SPELL);
                // scripted (increase crit chance ... against ... target by x%
                if(pVictim->isFrozen()) // Shatter
                {
                    AuraList const& mOverrideClassScript = GetAurasByType(SPELL_AURA_OVERRIDE_CLASS_SCRIPTS);
                    for(AuraList::const_iterator i = mOverrideClassScript.begin(); i != mOverrideClassScript.end(); ++i)
                    {
                        switch((*i)->GetModifier()->m_miscvalue)
                        {
                            case 849: crit_chance+= 10.0f; break; //Shatter Rank 1
                            case 910: crit_chance+= 20.0f; break; //Shatter Rank 2
                            case 911: crit_chance+= 30.0f; break; //Shatter Rank 3
                            case 912: crit_chance+= 40.0f; break; //Shatter Rank 4
                            case 913: crit_chance+= 50.0f; break; //Shatter Rank 5
                        }
                    }
                }
            }
            break;
        }
        case SPELL_DAMAGE_CLASS_MELEE:
        case SPELL_DAMAGE_CLASS_RANGED:
        {
            if (pVictim)
            {
                crit_chance = GetUnitCriticalChance(attackType, pVictim);
                crit_chance+= (int32(GetMaxSkillValueForLevel(pVictim)) - int32(pVictim->GetDefenseSkillValue(this))) * 0.04f;
                crit_chance+= GetTotalAuraModifierByMiscMask(SPELL_AURA_MOD_SPELL_CRIT_CHANCE_SCHOOL, schoolMask);
                // always crit against a sitting target (except 0 crit chance)
                if(crit_chance > 0 && !pVictim->IsStandState())
                {
                   return true;
                }
            }
            break;
        }
        default:
            return false;
    }
    // percent done
    // only players use intelligence for critical chance computations
    if(Player* modOwner = GetSpellModOwner())
        modOwner->ApplySpellMod(spellProto->Id, SPELLMOD_CRITICAL_CHANCE, crit_chance);

    crit_chance = crit_chance > 0.0f ? crit_chance : 0.0f;
    if (roll_chance_f(crit_chance))
        return true;
    return false;
}