The results of his earlier torture of Twin Twist aren't pretty, to say the least. Made doubly nasty by the fact that Topspin felt the whole thing.
Topspin: Get out... Get out of his mouth...
Partway through Issue #3, we're treated to this◊ pants-shittingly horrifying image of the comatose Fortress Maximus. He stays like that for the rest of the series, by the way.
Made even worse in the follow up-shots, where Energonstarts leaking out of his eyes.
Most of the deaths in the series are pretty horrific.
The pit fight ends with Kick-Off pulling Borehole's head off, sending up a massive spray of Energon.
Rotorstorm's death is this with a hefty dose of Nausea Fuel. His brains splatter EVERYWHERE.
In a similar vein, Pyro's fate. The Decepticon mob literally rips him apart, complete with a geyser of Energon erupting from the side of his neck as his head is pulled off.
Awesome as it was, Springer's killing of Stalker was still pretty messed up.
Snare basically gets his brain crushed by Impactor. Did we mention it was a Mercy Kill?
Before that, the entire side of his head is blown off, straight down to his brain module.
Impactor's murder of squadron X.
Ironfist's death and the circumstances surrounding it become deeply disturbing when given some thought. Imagine that there's a device in your head, slowly, inexorably tunneling through to your brain module. It can't be removed without killing you, so you're basically stuck waiting for it to reach its target. Oh, and you have periodic blackouts as a result of it moving further and further through your head, with each one carrying the increasing probability of being your last moments alive. Did we mention that your most trusted compatriot set the whole thing up to get his hands on your lab?
Skyfall's demise in "Bullets" isn't directly addressed, but from what we've gleaned about the effects of Gideon's glue, this is probably for the best.
Also from "Bullets": A Babu Yar survivor named Flattop succumbs to brain melt as a result of the glue. It's bloodless and without any external injury, but carries the implication that anyone present at Babu Yar could, without warning, be eaten away from the inside.
Springer getting his face ripped off by Overlord. Of special note is the fact that one of his optics is knocked clean out of his skull. The kicker, though, is when Overlord holds his face in his hand and mocks the other Autobots with it.
Overlord's burning endoskeleton after Ironfist detonated thousands of deterrence chips inside the Decepticon's body. He also gives a rambling threat to Verity somehow made all the scarier by his mangled form.
Overlord: Look at you. All brittle bones and ligaments and red, red ventricles, so sticky-soft and bendable... I wonder what noise you'll make when I pop your seams?