Praetor suit

The Praetor suit is the Doom Slayer's powered combat exoskeleton in Doom (2016), a powerful suit of armor of mysterious origins which was entombed by the demons of Hell in solid rock in an attempt to keep him from obtaining it if he were ever again to awaken. The UAC found both him and his suit during a special expedition into Hell by Dr. Samuel Hayden and brought the two back to the UAC Mars Base as a contingency against the chance of a demonic invasion.

Capabilities
The Praetor suit is a formidable device. Aside from basic defensive characteristics which can be augmented through the use of armor, it includes basic life support functions and, with sufficient upgrades, can add increasing protection against certain types of damage such as self-inflicted splash back or damage from exploding barrels. It can be upgraded with the Delta V jump-boots to add a thruster-powered mid-air jump.

The helmet of the Praetor suit has a context sensitive HUD which displays health status, armor, the currently equipped weapon and its ammunition, status of the BFG-9000 and chainsaw, current objectives met within the area, and other relevant information. It also serves as a display for the suit's built-in database, the Codex, which stores any information on enemies, weapons, and lore that the player comes across, and for the automap.

Praetor tokens
The Praetor tokens, items which can be obtained from the suits of fallen UAC space marines, can be used to upgrade the capabilities of the Praetor suit.

History
The Praetor suit is said by the demons to have been forged by one known only as "the wretch," and their writings claim that the suit was made in Hell itself. Despite this, the suit bears markings in English with Arabic numerals, and seems to have been manufactured by human corporations. This suggests that the actual origin of the suit may lie in another dimension from which the Doom Slayer originally came, eventually finding the Well and becoming the leader of the Night Sentinels. The game heavily suggests but never states with any certainty that this origin could be explained in one of the other games of the Doom series.

At some time after the Doom Slayer's defeat of the last Titan, the demons managed to separate him from the suit and seal him into a sarcophogus inside an ancient temple which they then collapsed onto him. The suit was itself then sealed into the solid rock whence it was later found by the UAC.

Trivia

 * The Praetor suit bears the designation "D22" in several places.
 * In Latin, a praetor was an elected magistrate who was in charge of the administration of civil justice, a rank just below that of consul.

Pre-release
During the Bethesda presentation the Doomguy's helmet had an "F90" designation. In the final release of the game, this writing is replaced with a rune-like symbol which seems to stand for the Doom Slayer himself, or for the Night Sentinels in general.