This is a Pathfinder Second Edition question.
I find the presentation of the rules in the Bestiary a little confusing, so I want to make sure I get this straight.
Zombie shamblers (Bestiary pg. 340) have
Melee [one-action] fist +7, Damage 1d6+3 bludgeoning plus Grab
So far so good. Reading this line, what I expect is that
Grab is a free effect that they get when they hit. If it said
grabbed, I would expect the grabbed condition to be imposed, but it doesn’t.
When we look up
Grab (Bestiary pg. 343), we find
Grab [one-action] Requirements The monster’s last action was a success with a Strike that lists Grab in its damage entry, or it has a creature grabbed using this action. Effect The monster automatically Grabs the target until the end of the monster’s next turn.
Here it gets a little hairier. The effect of using
Grab is listed as using Grab, a term which is not defined anywhere else, and also there’s an action cost listed.
I think the simplest reading is that the capitalization of
Grab in the Effect section is a typo. That still leaves the question of the action cost.
My expectation was that
1d6+3 bludgeoning plus Grab meant that it dealt the damage and automatically performed a Grab as part of the strike if it hit. That would mean that it costs one action for a zombie shambler to go from no contact to dealing damage and having the target grabbed.
The wording of
Grab makes me think that instead, the
plus Grab is just meant to indicate that hitting with the melee Strike fulfills the requirements of the
Grab universal monster ability. In that case, it would take two actions for the shambler to land the Strike and then use Grab.
I think the second reading is correct, but it runs so contrary to my expectations before I read the
Grab entry that it would be helpful to get another opinion.