IF (D100 + MOD <= Threshold)
THEN Hit
ELSE Resist

Threshold linked to difference in levels, but very irregularly. A possible error in original coding means that as you increase in levels, you don't always have a better chance of hitting your target (especially if that target is a higher level than yourself). It is as easy to hit a target 4 levels higher as it is to hit a target the same level as yourself, whilst there is far less chance of hitting a target only a single level higher.

Difference = Target Level - Your Level

Threshold values for targets of +/- 20 Levels
Diff Thresh Diff Thresh Diff Thresh Diff Thresh
20 0 10 5 0 50 -10 85
19 1 9 27 -1 55 -11 87
18 2 8 24 -2 60 -12 89
17 3 7 21 -3 65 -13 91
16 4 6 18 -4 70 -14 93
15 5 5 15 -5 70 -15 95
14 13 4 50 -6 73 -16 96
13 11 3 45 -7 76 -17 97
12 9 2 40 -8 79 -18 98
11 7 1 35 -9 82 -19 99
            -20 100
[Graph]

MOD = TR Bonus + Aim Bonus + Ment Bonus

TR Bonus - See [Target Resist] section.

Aim Bonus = +80 to -80 for Maximum Allowable Miss to Direct Hit
Ment Bonus = +15 if the target is a Ment
[Graph]

Example

A 15 ment attacks a 15 cleric with P5, scoring a direct hit
The random D100 roll scores 75

Difference = 15 - 15 = 0
Therefore (by looking at the table) Threshold = 50

	MOD			= P5 + Direct Hit
				= 45 + -80
				= -35

	D100 + MOD		= 75 + -35
				= 40

40 is less than the threshold value of 50, so the attack hits.