What type of action is required for the aberrant promethean to maintain a grapple with its tentacles and does it get the -20 penalty associated with grab when maintaining the grapple with its tentacles?
While it's not specifically stated, it has grab and that seems to be the point of its ability - that it would grap creatures and hold them in its tentacles while continuing to battle other opponents.
The way I ran it, once someone got transferred to the tentacles, the only way they could get out was by escaping themselves. I just made it so there was no maintain check in the tentacles.
A little harsh, yes, but I have a pretty powerful party and it ended up not affecting much in the end.
I think the tentacles would have to make some kind of check since it says the tentacles grapple with the same strength as the slam attack. I think I'm going to let the tentacle act as a free action during the AP's standard or full attack.