A creature with this special attack can crush an opponent, dealing bludgeoning damage, after making a successful grapple check. The amount of damage is given in the creature’s entry. If the creature also has the improved grab ability it deals constriction damage in addition to damage dealt by the weapon used to grab.
Another way to phrase it is as follows:
Whenever a creature makes a successful grapple check, then after that check resolves, the creature deals additional bludgeoning damage. If the creature has improved grab, it deals the improved grab's weapon damage plus the constriction bludgeoning damage.
Nothing in the description of entangling staff would change that definition. Next we examine the actions allowed by entangling staff:
Release: You release your opponent from the grapple. Some vines remain clinging to your foe, leaving it entangled for the duration of the spell. You can attack different enemies in later rounds with the staff, potentially grappling and constricting or entangling them.
Maintain: You maintain your hold. In subsequent rounds, you deal constriction damage with a successful grapple check. You can then choose to release or maintain the hold again.
Compare those actions with those stated in the rules for grappling:
Maintain Grapple. To maintain the grapple for later rounds, you must move into the target’s space. (This movement is free and doesn’t count as part of your movement in the round.)
Moving, as normal, provokes attacks of opportunity from threatening opponents, but not from your target.
If you can’t move into your target’s space, you can’t maintain the grapple and must immediately let go of the target. To grapple again, you must begin at Step 1.
The rules for entangling staff are simply restating the rules for grappling: you must either maintain the grapple or not. However, if you choose to release your opponent from the grapple instead of maintaining it, the opponent is left entangled. Note that by the rules listed here, you will only leave the opponent entangled if you release them from the grapple. If your opponent escapes the grapple, they will not be entangled.
Grappling with the entangle staff is identical to grappling normally with the following exceptions:
- The caster may begin grappling as a free action that does not provoke attacks of opportunity by striking the target with the staff
- The caster gets a bonus of +8 to its grapple checks only for grapple checks resulting from the melee strike with the staff (so enemies that initiate grapple with the caster or grapples the caster joins without striking with the staff do not get this bonus -- the opponent must be affected by the staff)
- The caster's successful grapple checks deal 2d6 constrict damage from the vines created on the staff when the grapple begins and on any checks while the grapple is being maintained
- If the caster releases the target from the grapple, the target is entangled for the remaining duration of the spell