I'll start out by saying that I don't have any books infront of me so I'm going by memory. The improved grab does allow a creature to make a grapple check as a free action on a successful hit. That hit does the normal melee damage from the attack. I don't think the constrict damage starts until the following round, but I could be wrong (I would check under constrict in the MM). A PC being grappled does several things to them. One of which cause a lose of their Dex bonus to AC. It will also cause the PC to switch to a light weapon (I hope they have some) if they can't break the grapple. The spell casters will have a worse time since they can only cast spells that don't have somatic components while grappled. A smart group will try and stay at range of this thing. I also think that once something is being grappled by it, there is a 50% chance to hit the grappled PC when using ranged attacks.
Now for the swallow. I don't know what the rules say but I would assume that it can only swallow one creature of one size category smaller than it at a time (or two creatures two size categories, etc.). I don't think it would be able to swallow more until that creature is dead. A creature swallowed can still attack, but once again it requires a light weapon.
So yes, if a party just goes in and starts wailing on it could turn ugly very fast. Reading your post I now have to think how my group will be able to handle it. At least I have a month or so before they get to it.
A grappling creature can't do anything else in a round unless it takes a -20 penalty on grapple checks. So you could do that! Grapple the fighter first and on the second round it tries to attack someone else, so she can't concentrate on the grappled fighter who could make it out (it has a +15 to grapple now).
A grappling creature can't do anything else in a round unless it takes a -20 penalty on grapple checks. So you could do that! Grapple the fighter first and on the second round it tries to attack someone else, so she can't concentrate on the grappled fighter who could make it out (it has a +15 to grapple now).
Antoine7 is right. If a creature tries to hold a grapple on another creature with only one of it's appendages (say a bear holding you down with one paw) then it takes a -20 on its grapple check, although the grappling creature is not considered grappled.
Here is kinda how I would see a fight go. It would try to get into melee with as many PCs at once spreading out its 6 attacks amoung the group. Then it would choose to grapple probably the smallest opponent (using its full grapple). The next rould it would swallow the grappled opponenet. If that is a free actio then it would once again attack all opponents in range. When the attacks are done it would grapple the second smallest as a free action (taking a -20 on the grapple). After that it would use it free appendages to attack whater is around while constricting the grappled foe and digesting the swallowed foe. But its actions really do depend on what the party does. :)
Well, there's still natural 20's... no, it deals damage too fast for that to have a real chance of success.
Also, it's an opposed check. Natural 20's don't mean an automatic success.
I'd rule the creature could only swallow one opponent at a time. If I remember MM entries on swallowed creatures right, most monsters have a rated capacity of how many creatures of a given size fit in the gullet at any one time--I'd rule that once its gullet is full it can't swallow any more creatures for the duration of the combat, unless one that's inside gets out.
Like the tactics of attacking all opponents in range, then choosing one to grapple--I wouldn't necessarily pick the smallest--after all, the thing's been starved for a couple of days to make it hungry and aggressive, right? If I'm the Froghemoth, I'm going for the biggest morsel, as long as it looks like I can grab it and swallow it with reasonable ease.
As for shooting at it while it's grappling a party member, since it is a large (or huge, can't remember) creature, you can target a different part of it (i.e. a different square) from the one in which the grappled ally is held and negate this penalty. (Maybe on a natural 1 you miss so badly that you run the risk of targeting a random neighboring square, which might be the one in which your ally is being held.
As for the party, if the party wizard and rogue charge in there instead of staying back to pepper it with ranged attacks, they bloody well deserve a tour of its digestive tract!
Asked this questions at Wizards message boards. Received this response from mvincent: "Just one.
Improved Grab says the creature uses "the part of its body it used in the improved grab to hold the opponent". So it could not grab multiple opponents with it's mouth (as the mouth is already occupied with the first occupant, and while so occupied it can not be used for susequent attacks).
Swallow whole says the creature must "begin its turn with an opponent held in its mouth" in order to swallow it.
This mouth issue not as clear in 3.0, but the 3.0 FAQ clarified it, and it was later incorporated into the 3.5 rules."