Finally, the Dinobot combiner that "The Beast" sort-of kind-of not-really foretold!
Wave 2 Power of the Primes has two the final two Dinobots, allowing Volcanicus to be properly combined. Sludge owes a lot of his parts to Slag. In robot mode, his thighs, shins, and upper arms are the same. From the waist up, he transforms backwardsly, with his front becoming the dinosaur back instead of the dinosaur stomach. Similarly to Slag, Sludge's brontosaurus head/neck closes around the robot head, concealing it.
The original Sludge toy had you fold his forearms up against the insides of his upper arms, with his brontosaurus toes at the elbows. This new toy just leaves this transformation step out of the equation and leaves the brontosaurus toes at the wrists. The instructions want you to bend his arms at the elbows for dinosaur mode, but I think I like them better straight. It's more of a brachiosaurus look, but oh wells.
(I'm going to call him a brontosaurus, since I'm pretty sure the character design is old enough that he's not meant to be an apatosaurus.)
Snarl, the stegosaurus, is all new! He keeps his thagomizer behind his head, but he otherwise transforms similarly (surprise!) to his other quadropedal Dinobot friends. His head's a little smaller than the others, possibly since it needs to hide inside the combiner port cavity within his own chest, rather than inside a dinosaur part. Instead of being flatfooted like the others, his dinosaur hind legs stand on their tippy toes.
Sludge, Snarl, Grimlock, Swoop, and Slag all combine to form VOLCANICUS! Volcanicus is actually a pretty good combiner. A lot of anguish has been thrown about over how wide his shoulders are, but so long as you plug those extra two combiner fists into his abs, it's really not a problem in person. He's wide, sure, but his torso tapers from the waist properly to make it look fine. His wideness merely makes him look mighty.
The other option for the two extra fists is to plug them into the back of the feet for additional stability. He's not going to need this. Well, he's not if yours has the same plastic tolerances as mine. The biggest threat to my Volcanicus's stability is that one of his feet likes to rotate a little to the right, which can lead to him ultimately losing traction and doing the splits. Extra heels would not solve this. Tighter 5mm pegs at the ankle, yes, but not heels.
The major negative to Volcanicus is his lack of a weapon. In the cellphone game Earth Wars, Volcanicus gets an upsized version of Grimlock's Fall of Cybertron sword. You can try giving him the FoC toy's sword, but it was already a little undersized for the Voyager Class toy. Being held by a giant combiner makes the sword look like it's meant to serve cheese on a plate. There's some third party options, one of which is $50 and includes a bunch of extra stuff I'm absolutely not interested in, and at least one Shapeways sword. For the time being, at least, my Volcanicus is gonna have to fight people with his bare fists.