[Figback65]

Found it I think in attack.cpp

attack.cpp

// called when a mob is attacked, does the checks to see if it's a hit
// and does other mitigation checks. 'this' is the mob being attacked.
bool Mob::CheckHitChance(Mob* other, SkillUseTypes skillinuse, int Hand, int16 chance_mod)
{
/*/
		//Reworked a lot of this code to achieve better balance at higher levels.
		//The old code basically meant that any in high level (50+) combat,
		//both parties always had 95% chance to hit the other one.
/*/

	Mob *attacker=other;
	Mob *defender=this;
	float chancetohit = RuleR(Combat, BaseHitChance);

	if(attacker->IsNPC() && !attacker->IsPet())
		chancetohit += RuleR(Combat, NPCBonusHitChance);

	Log.Out(Logs::Detail, Logs::Attack, "CheckHitChance(%s) attacked by %s", defender->GetName(), attacker->GetName());

	bool pvpmode = false;
	if(IsClient() && other->IsClient())
		pvpmode = true;

	if (chance_mod >= 10000)
		return true;

	float avoidanceBonus = 0;
	float hitBonus = 0;

and more I didn't wanna spam post with

EDIT :

	if(attacker->IsNPC())
		hitBonus += (attacker->CastToNPC()->GetAccuracyRating() / 10.0f); //Modifier from database