Barry and Team Flash go from keeping four bus metas safe to zero in The Flash's "Lose Yourself." What begins as an attack on S.T.A.R. Labs ends in a handful of dead metas — Ralph Dibny included — and dark matter in the hands of DeVoe. But why does the Thinker need dark matter on The Flash? From the moment fans met the Thinker, he's been focused on one thing: knowledge. He wants to know everything, he wants to be the smartest man alive, and dark matter has, in the past, given him that power. But why now? And why, specifically, did he need dark matter from S.T.A.R. Labs?
Before DeVoe can get his hands on dark matter, he needs the bus metas. In "Lose Yourself," Barry and Ralph track down the final bus meta, Edwin Gauss, and, honestly, he's a little too easy to find. A hippy with little to no interest in the goings on of Central City metas, he got the power to create pocket portals, secret holes in the universe that allow him to travel through space and create spaces no one else can reach. Fans will remember that a few episodes back, Cisco discovered that the Thinker's lair was in one such pocket dimension, and with Edwin in custody and willing to help, Ralph hatches a plan: get Edwin to open a portal to DeVoe's lair, and kill him.
Ralph's plan to kill DeVoe is, unsurprisingly, not Barry approved, but Barry's insistence that Dibny not kill the Thinker is likely going to come back to haunt him. After stopping Dibny from going on his suicide mission, Barry decides that, while risky, Dibny's plan is pretty much the best chance they've got. He gets Edwin to open a portal to DeVoe's lair, and, armed with what is essentially a superpowered tuning fork, he enters with Killer Frost and Vibe, only to find the lair...empty. Barry played right into DeVoe's hands.
The Thinker uses the distraction of Edwin's portal to break into S.T.A.R. Labs himself and go after the bus metas in the pipeline. Using his acquired meta powers to distract Dibny, DeVoe kills all three bus metas being kept safe in S.T.A.R. Labs, leaving only Dibny alive. Using the tuning fork, Dibny is able to subdue DeVoe, and he doesn't kill him, handcuffing him instead. Unfortunately, it seems those handcuffs could really use some work. DeVoe breaks out of them and latches onto Dibny, sucking his meta powers out of his head, taking his powers and his body, but killing the real Ralph Dibny for good.
At first, it looks like DeVoe's main goal at S.T.A.R. Labs is to finally get all the bus metas, but in the very last minute of the episode, another motive is revealed. He comes out of his attack on Team Flash with new meta powers and a vial of dark matter, taken directly from Reverse Flash's time vault, courtesy of Harry, who overloads his own thinking cap with dark matter when he realizes DeVoe has broken in. Back at the Thinker's lair, DeVoe tells his wife that the dark matter is the key, not only to enlightenment, but to the destruction of S.T.A.R. Labs. Cleary, this was his end game. He didn't just want the bus metas, he wanted the dark matter. The question is, for what?
Dark matter is the thing that started it all, it's what gave the Thinker his powers in the first place. DeVoe telling his wife that dark matter is the key to enlightenment could mean a few things. Most obviously, it could mean that he plans on dosing himself with it. Thanks to all the meta powers, DeVoe is stronger than ever, which could mean his body is more capable of higher dark matter dosages. More dark matter could, in theory, increase his cognitive abilities (which are already heightened), making him even stronger. Alternatively, he could be planning on dosing someone else, or many someones.
If DeVoe uses the dark matter on himself and manages to make himself all knowing, it would certainly mean the end of Team Flash. And Team Flash can't afford to lose anything more. Not only did the Thinker kill Dibny, he also took away Caitlin's Killer Frost powers, leaving Team Flash two metas down and out of local heroes to call upon. Hopefully they'll come up with something before the Thinker uses the dark matter and sets final plans into motion.