gistfile1.cs

float GetPvESpellHitRate(byte playerLevel, byte targetLevel, byte spellLevel)
{
	float hitrate;
	if ( playerlevel > targetLevel) // Player > Mob, no base miss rate, 0.5% miss per spelllevel lower than moblevel
		hitrate = 1 + (spellLevel - targetLevel)/200);
	else if ( targetLevel == playerlevel) // Player == Mob, 15% base miss rate, 0.5% miss per spelllevel lower than moblevel
		hitrate = 0.85 + (spellLevel - targetlevel)/200);
	else // Player < Mob, guessed formula
		hitrate = 0.85 - Math.Sqrt(targetlevel - spellLevel) * 9;

	hitrate > 1 && hitrate = 1; // cap at 100% just to be sure
	hitrate < 0.55 && hitrate = 0; // any hitrate < 55% results in 0% hitrate

	return hitrate;
}