The Scagdead is created when the t-Abyss virus undergoes a secondary mutation within a human host body. This mutation occurs when the victim has a stronger-than-normal resistance to the virus, slowing its spread. The result is the grotesque, disproportionate body characteristic of a Scagdead - this transformation occurs once in roughly a thousand hosts.
Scagdeads appear as huge, fleshy, lumbering creatures with pillar-like legs. They are slightly taller than an average human, but much bulkier. Their coloration is mostly grey, save for a flesh colored patch where the remnants of the original human host remain. The host's head is effectively displaced by a massive fanged maw which opens vertically. In some cases, the host's head can repeat some words and phrases - this is dependent on the extent of the mutations on the head. The Scagdead's "human" half appears to be conscious as it says "stop it, I'm human"(when attacked), "get away, there are monsters here", "don't run from me, I'm human" etc. This also indicates that the previous host is still slightly aware of its surroundings, but oddly unaware of its fate.
The left arm of the creature remains virtually unchanged from a regular human's, albeit emaciated and with an additional flipper-like appendage directly beneath it. On the other hand, the Scagdead's right arm has been grotesquely mutated - it has become extensively muscular (although obscured by folds of flesh) and tipped with an organic mimicry of a buzz-saw. This appendage can be swung multiple times in quick succession, mimicking attacks that of a Chainsaw Majini or Giant Chainsaw Man, and serves as the Scagdead's primary means of attack.
Scagdeads are also capable of vomiting up clam-like objects that serve as Bear Traps. These objects can stall the player, allowing the Scagdead to close in and attack, but they can also be destroyed with a single bullet from any gun.