A Gaming Glossary: D

Damage boostTaking damage to get past an enemy or obstacle, or to reach an objective faster than would be possible by other means.

Exactly what is considered a damage boost varies by game. In the broadest sense, if you are taking damage to do something that would be otherwise slower or impossible, you are damage boosting. Running into an enemy and then walking through it during the resulting iframes is damage boosting in this sense. This is how the term is used in, for instance, many platform games.

In a stricter sense, damage boosting means taking damage to actually “boost” your character’s position — to gain extra height on a jump, for instance, or clip through a wall or ceiling. A famous and somewhat extreme form of this kind of damage boosting is rocket jumping.
Death abuseUsing deliberate deaths to gain some advantage in the game. The classic example is a death warp, but death abuse may also involve, e.g., taking a planned death to refill one’s health before fighting a boss.
Death warpTaking a death to instantly reset the player’s position in the level or map. The ability to die and respawn at specific points in the game can represent a significant time save in some games (Zelda 2 is one good example). Thus, the inclusion or exclusion of death warps is an important part of speedrun categorization in these games. Sometimes, death warping is part of the execution of a wrong warp.
DeathlessWithout taking a death. Whereas terms like death abuse suggest that the player intentionally took a death for some strategic reason, a deathless category excludes player deaths for any reason, whether accidental or deliberate.