Combat Level

Sulu's, sir. One of 'em!

I generally don't use the combat tables in the DMG any more, having re-written them some time ago to make armour versus weapon modifiers easier to use. I'm not going to go into that system right now, but since I mentioned Combat Level (CL) in the stat blocks for the Weeping Medusa I thought I'd explain the basic system (without weapon Vs armour) here.

"Combat Level" appears in the DMG as well as its synonym "Combat Ability".

Combat level is simply a number representing the level of fighter that something fights as. So a 5th level cleric has a basic combat level of 3. A 4th level fighter with a +1 to hit from strength and +2 from a magical sword has a combat level of 7.

In a standard combat, the attacker rolls 1d20 and adds their combat level to the die and the DM then adds the target's AC to that. If the result is 21 or more, it's a hit. Any roll of 20 is counted as 25.

If combat level is so high that a figure can't miss, then they hit automatically with a bonus to damage equal to (CL+AC-21), so a 15th level fighter attacking someone with no armour will do 4 points of extra damage per hit.

My original PDF with more details is here, but here's some tables of combat level as well:

Monster HD	CL
<1-1	0
1-1	1
1	2
1+	3
2-3+	5
4-5+	6
6-7+	8
8-9+	9
10-11+	11
12-13+	12
14-15+	13
16-17+	14
18-19+	16
20-21+	17
22-23+	18
24-25+	19
26+	20

Cleric Lv	CL
1-3	1
4-6	3
7-9	5
10-12	7
13-15	9
16-18	11
19+	12

Thief Lv	CL
1-4	0
5-8	2
9-12	5
13-16	7
17-20	9
21+	11

MU Lv	CL
1-5	0
6-10	2
11-15	5
16-20	8
21+	10