* [[StarfishAliens The Scrin]]. [[WordOfGod Peptuck has said]] that he wanted to make it clear just how terrifyingly powerful they are compared with everyone else, and [[PunctuatedForEmphasis IT. IS. WORKING.]]
** The Scrin have apparently gone to work on the husks in the same way the Geth did in the original game. Instead of a n electrical blast, they're now armed with energy cannons on their arms, and their hands are ''four foot long blades.''
** Buzzers. Everything about the Buzzers. They swarm you en masse, break into your armor, and then chop anything organic they find [[LudicrousGibs into soup.]] In ''seconds.'' Shepard herself is completely terrified of these things, and [[ScarsAreForever with good reason]]. Going by her flashback to Akuze, there was a Scrin Buzzer ''cutting up through her nose''. Her dream in "Ghosts" takes their nightmarishness to even greater heights, because she gets attacked by a swarm of them and, unlike in real life, ''doesn't die''. [[AndIMustScream She's just lying there, getting sliced to pieces bit by bit by the swarm while the vision progresses]].
** [[EliteMook Ravagers.]] [[NighInvulnerable Shepard pumped an entire clip of grenades into]] ''[[NighInvulnerable one,]]'' [[ImplacableMan and it still just kept coming.]] *shudder*
** The Battlemind. Unrelenting, and nearly unstoppable (to the point where an entire belt clip of sonic grenades - the Scrin's Kryptonite - detonating on top of it merely stuns it) and armed with a weapon that lets it tear apart walls and vehicles and infantry squads with casual ease. And on top of that? ''It has a sense of humor''.
** The Scrin cruiser that defeated the turian cruiser ''Valadictum''. It effectively tanked everything the turian ship threw at it while firing back [[spoiler: tiberium-tipped directional flak shells loaded with ''nuclear explosives'']]. And then it casually outmanuevered the ''Valedictum'', disabled it, and [[spoiler: instantly took control of the entire crew with Masterminds]].
* When Kane showed up at the end of chapter five, [[HellYesMoment the fanbase was roaring their approval]], anticipating that the Tiberian Saga's favorite {{Chessmaster}}, DarkMessiah, and all around MagnificentBastard would start playing everyone like a piano. And then, in the very next chapter, after doing ''just that' to the entire Citadel Council chamber, with Shepard tailing him after he makes a discreet exit. In the ensuing conversation, Kane says three little words that made the fanbase's collective hearts stop beating: "I don't know."
* From Chapter 14, we have Shepard's Tacitus-induced nightmares/visions. A lot of people dying [[CruelAndUnusualDeath horrible deaths]] at the hands of the Scrin, the Reapers, and even [[spoiler: by a Prothean's hand.]] Also? [[spoiler: [[OhCrap The Collectors have begun their assault on humanity early.]]]]