Sunday, March 4, 2012


One of the innovations in the d20 rules that was made by the Paizo folks was the Combat Maneuver Bonus/Combat Maneuver Defense scores.

Basically they took all the fiddly 3E combat actions (disarm, trip, bull rush, grapple, etc.) and turned them into this formula:

CMB = BAB + Str + any special bonuses (in other words, a basic attack roll, modified by feats/class abilities).
CMD = 10 + BAB + Str + Dex + any special bonuses.

I'm considering using the basic formula for my Classic D&D games for whenever anyone wants to do something like swinging from chandeliers, flipping their cloak over the opponent's head, throwing sand in their eyes, or the above grapple/disarm/trip type stuff.

I'm already using ascending AC/attack bonus, so this would be easy enough to add in.  For monsters, they just get normal attacks, and 10 + HD for CMD (maybe the creatures that get a Strength bonus/penalty to damage could factor that in as well).

Simple, easy, and hopefully will make for more dynamic combats than simply "roll to hit, roll damage, rinse and repeat."


  1. Forgive me, Lord G, but I am both a) extraordinarily dense (my wit is akin to osmium) and b) completely unfamiliar with Pathfinder. Could you explain how CMB and CMD work?

  2. Alright. So there are the formulae above. A Fighter at first level has a +1 BAB (Basic Attack Bonus), and let's assume a +3 Strength modifier and a +1 Dex modifier.

    His CMB would be +4 (+1 BAB, +3 Str) and his CMD would be 15 (10, +1 BAB, +3 Str, +1 Dex).

    He's fighting an orc with +1 BAB and +2 Str, +0 Dex. The orc has a CMB of +3 and a CMD of 13.

    The Fighter wants to trip the orc. He rolls an attack (d20 plus CMB of 4) and has to beat the orc's CMD of 13. Let's say he misses this round, and the orc stays on his feet. The orc decides to disarm the fighter, and rolls d20 plus CMB of 3 against the fighter's CMD of 15. He hits, so the fighter is disarmed.

    Basically, CMB replaces the normal to-hit bonus (although in the case of my example it's the same, feats can modify it). CMD replaces AC for the attack as the target number to beat.

    In a real example, my Paladin from our recent game had the Improved Disarm feat (+4 to CMB and CMD with regard to disarm attempts), and used a flail (+2 to disarm and trip attempts). He had a +2 Str bonus and no bonus to Dex. At 4th level, my CMB was +6 (disarm +12, trip +8) and my CMD was 16 (20 vs. disarm).

    My AC was 21 so it was actually easier for monsters to bullrush, trip, grapple, etc. against me. In fact, in the final battle against an Aspect of Hextor, the aspect picked me up and threw me against the wall as a combat maneuver. I was pretty good at disarming opponents, though, at the end (when we fought ones with weapons).

  3. So, for the flashy stuff, you roll to be beat CMD rather than AC, correct?

  4. It's a nice system. I think in B&T I was using a AC vs. maneuvers of 15 + Dex (or Str, in some cases) with a normal attack roll against it.

  5. @BV - exactly. And having one simple system to resolve lots of flashy stuff makes it easy to try just about anything, especially for the players who grew up on newer editions, where there's a distrust of DM fiat.

  6. Yes, I can be taught!

    But "distrust of DM fiat" makes this humble pirate sad.

  7. distrust of DM fiat makes me sad as well, but I've got a few of those folks among my player pool here, and it's a small pool so I take what I can get.

  8. I agree that Combat Maneuvers are pretty awesome and can add more realism to a combat. There is a guy on the Microlite forum who just released his Pathfinder Lite V2. You might glean some insight from that.

    Also, remember Telecanter's Receding Rules that Justin posted awhile back. Here's an "elegant solution" for combat maneuvers.

    Simple Combat Maneuvers
    Joshua Macy
    “Tell me what you want to do to your opponent before you roll to hit. A critical means that happens, a normal hit means your foe decides
    whether to let that happen or take damage instead.”

    Possible maneuvers to try:
    Knock Down
    Push Back
    Switch Positions
    Slip Past, etc.

    The innovation here is the decision point, which allows tactics to enter the abstracted battle without overwhelming it. It also allows for context to affect the decision without trying to codify all possibilities.