Do rends stack?

[S_Grey]

Say, for instance, if a certain shapeshifter went shopping around and found out that she could have more than one rend for her big, sharp claws? If she was already level 12, and a feral creature, and took the Open lesser chakra (arms) feat from magic of incarnum for her Girallon arms, would her rends deal more damage?

Naturally that gives her two sources for Rend, but the question is: do those sources stack?

If her claws did (3d6+14) damage, would she rend her targets for (6d6+28) or (12d6+56) damage after she hits with both of her claw attacks?

[Larrx]

I do not believe that multiple sources of rend stack in that way. If you had four natural attack, or unarmed strikes, or whatever you trigger rend multiple times per round, but I do not think it works the way you've presented it.

That being said, if I were the DM, I would allow it. Melee deserves nice things :)

[The Viscount]

I'm assuming for the purposes of this question that your DM has allowed you to gain rend without having 12HD of monster and that you also either took shape soulmeld or have levels in a meldshaping class.

There isn't exactly any text that says that the rend stacks, but that's likely because all rend other than girallon arms is weapon-specific. This also means there's nothing that really says you can't do this, so I suppose technically you would stack them. However, note that when stacking two 2X modifiers, the result is 3X, not 4X.

[Fax Celestis]

Let's start here. "Rend" is a special attack. Here's the exact text from the Troll MM entry:

Rend (Ex)
If a troll hits with both claw attacks, it latches onto the opponent’s body and tears the flesh. This attack automatically deals an additional 2d6+9 points of damage.

And from Girallon:

Rend (Ex)
A girallon that hits with two or more claw attacks latches onto the opponent’s body and tears the flesh. This attack automatically deals an extra 2d4+9 points of damage.

And from Rules Compendium:


If a creature that has this extraordinary special attack hits with the specified natural attack, it latches onto the opponent’s body and tears the fl esh. The rend attack deals damage equal to that dealt by the creature’s natural weapon + 1-1/2 times its Strength bonus or its full Strength penalty

They are similar abilities with different triggering conditions. In both cases they deal double claw damage plus 1.5*STR mod damage.

Personally, I would allow you to have multiple rends, but they would trigger independently. A half-troll girallon (horrifying monstrosity that brings to mind) would rend for 2d6+9 and 2d4+9 if it hit with two claws. If you had a rend that triggered on a claw + bite success and a rend that triggered on four successful claw attacks, you'd only get both if you hit with four claws and a bite.

It's a vague area, though, and not really defined. In one hand, you have that it's a special attack, and having the same thing more than once doesn't give it to you twice unless it otherwise says so. On the other hand, you have similar abilities with different triggering conditions: you can have two breath weapons, after all. I'm inclined to lean on the latter option (you have two abilities that trigger differently) but YMMV, AYDM.

[Necroticplague]

Yes. All rends are "if x then y". Every time you meet the x, you get the y. The fact two different y share an x is irrelevant.