Each of the combiner teams so far includes a new dude who replaces one of the traditional dudes. Alpha Bravo replaces Slingshot, Offroad replaces Wildrider, and Rook replaces Groove. Slingshot, Wildrider, and Groove are all still available somehow, so it doesn't bother me so much, plus it gives us these new guys. I like new guys! And the new guys so far have been more interesting than the folks they replace. Rook is the best example of this so far. He's probably the best toy of the Deluxe Combiner Wars guys so far.
What makes him stand out is that, unlike Alpha Bravo and Offroad, who are really Vortex and Ruckus, Rook is an entirely new design. He gets to be his own dude, rather than a "pretool" of somebody else. I mean, he's probably going to end up being a pretool for somebody else eventually, given how often these toolings are reused in some manner, but he's seemingly entirely himself.
And since he's new we get an interesting idea or two from him, since he starts out as a blank slate. He's wide and bulky, unlike his peers. His head is designed to look like a rook piece from, y'know, chess, which may make him the first Transformer guy named Rook whose name makes some sort of sense. He transforms differently from everyone else, incorporating a rear backpack of sorts that satisfyingly snaps into place in each mode. He's got ankle joints, which is a luxury in this line.
But most importantly to me, he's got Hulk hands. Instead of the usual 5mm peghole inside his hands, this hole is instead sculpted in front of them, so that you can take a combiner fist and plug one in, giving him pounding power. You can double up on them, or even quadruple up on them if you plug another two into his shoulders. Not only is this super cool, but it also frees up weapons from other characters who look kind of mismatched holding large-ass pieces of artillery, like First Aid.
Over in Japan, they're making a Deluxe-sized Groove exclusive to their country and ditching Rook. I feel a little bad for them. We still get Groove as a Legends Class chestpiece over here, and Rook is great.