Of all the combat rules, grappling is easily the main villain of complexity. It’s a rule that you know must have worked for the game’s designers at the time, but in retrospect it’s perhaps needlessly complicated. When you add in the Attack of Opportunity cost, players rarely ever use grapple, trip or disarm unless they’ve deliberately built a fighter around special combat manoevers. It’s an extra challenge on Dungeon Masters who have to run monsters that grapple.
Since it’s complex, I’m going to try and simplify it. Let me know if this helps you any.
First up is the grab. It’s just a regular attack roll, except that you use the opponent’s touch AC (ignores armour, natural armour and shields). If you haven’t taken the Improved Grapple feat, however, your opponent gets an Attack Of Opportunity first, and if he hits and deals damage, your grapple attempt fails. Remember that starting a grapple takes only one attack, if you have multiple attacks you can make multiple grapple attempts – your opponent, meanwhile, probably only has one Attack of Opportunity per round.
Did you manage to grab? Good! (If not, better luck next round.) To secure the grapple, you must beat your opponent in an opposed grapple check – essentially, these are Strength checks (1d20 plus your Strength modifier). If you succeed, you’re now grappling, and you automatically deal damage as an unarmed strike. If you fail, you’re back to square one. There are other modifiers to grapple checks: +4 or -4 for every size class above or below Medium, and +4 for having the Improved Grapple feat. At the end of the round you can either automatically move into the opponent’s square, or end the grapple.
While grappling, you and your opponent have a limited range of actions – that’s kinda the point of grappling. The following actions can be performed by defeating your opponent in an opposed grapple check:
- Escape from the grapple (attack action): your opponent will probably want to do this
- Damage your opponent (attack action): Deal damage as an unarmed strike – pretty good if you’re a monk
- “Pin” your opponent (attack action): Hold a grappled opponent immobile for one round, -4 to AC to people outside the grapple
- Damage someone with his own weapon (attack action): Additionally, you must succeed at an attack roll with -4 penalty
- Draw a light weapon (move action)
- Move half your speed (standard action): Otherwise, you can’t move while grappling
- Retrieve a spell component (full-round action): If you’re grappled as a wizard, you’re in big trouble
You can also perform the following actions, without making a grapple check:
- Attack (attack action): You suffer a -4 penalty to the attack, and can only use a light weapon, natural weapon or unarmed strike – so no longswords
- Cast a spell (as usual): A grappled spellcaster is in trouble, but he can still cast spells – as long as they have no somatic component, aren’t more than a standard action, don’t require spell components unless he has them in hand (see above), don’t require precise and careful action, and he make a difficult Concentration check. Not a good position to be in.
- Activate a magic item: Other than a wand or staff
But why grapple at all? There are benefits and drawbacks, which apply equally to anyone in a grapple regardless of who started it. First, they don’t threaten any squares, so they can’t attack anyone but you (and even then only with light weapons and at a penalty). Second, they’re weakened defensively, and lose their Dexterity bonus to AC against anyone except who they’re grappling with. Third, neither can move without making grapple check. Finally, their options are limited to the list above. The best times to grapple are when your opponent suffers more from the penalties than you do. As a bonus, grappled opponents are vulnerable to a rogue’s sneak attack.
Whether you’re a player or a Dungeon Master, grapple is good for shutting down a strong opponent. It’s especially effective against spellcasters (who cannot cast and may find it difficult to escape a grapple), creatures smaller than you (who tend to have low Strength and have a size penalty). It even works against some fighter types, who cannot use large weapons, ranged weapons, dual weapons or reach weapons while grappling, nor can they move to target weaker characters, and their base attack bonus doesn’t help them all that much to escape the grapple.
In summary: To grapple, make a touch attack (provokes attempt-ruining AoOs!) then an opposed Strength check with +4/-4 modifiers for size past Medium. Deal unarmed strike if you’re successful. Opposed grapple checks as attack actions to escape the grapple, damage opponent with unarmed strike, or pin opponent immobile for a round. Alternatively, you can attack with a light weapon but at a -4 penalty.