Enrage Timer is a game mechanic used in Diablo III to ensure boss battles are quick on Torment difficulty, and encourage the player to gear up well before proceeding to killing the next boss. In other words, it prevents a boss from being killed by the "thousand cuts" tactic over an unreasonably long time.
If the battle is not finished after a few minutes, bosses can do a variety of things. One is buffing the boss' damage, or debuffing the player. The effects will increase until the battle is ended. Other bosses gain or empower an ability beyond reasonable survivability. The time and effects vary by boss, and not all bosses have them.
The idea is making the combat harder after a certain amount of time, up to the point where the battle becomes unreasonably hard for an adequately geared player. A general rule of thumb to keep in mind is to try and keep on damaging the boss monster most of the fight. The reason for this is twofold. Firstly, once the boss monster is killed, if it had any minions summoned, they will prove to be of little to no threat afterwards, or will even die outright. Secondly, for most adequately equipped players, most of the attacks used by the boss monster will prove easily survivable and/or avoidable, especially if they have a high degree of endurance and healing compared to the difficulty level.
There are two types of enrage timers: hard and soft.
- Hard timers have a set time, and once it expires, the fight instantly becomes much more difficult (though not outright impossible).
- Soft timers gradually increase the difficulty of the fight over time, and continue to do so until that encounter ends, be it with the death of the Nephalem, or the boss.
See individual boss pages for timers (mostly 3 or 4 minutes) and effects of the enrage. Known effects include:
- Covering the entire battlefield with harmful effects that at some point will generally be unavoidable without the proper immunity amulet for the encounter (Ghom, Belial, Adria)
Some bosses, most notably Diablo and Malthael, do not have enrage timers. This is due to these boss fights being complicated enough, and these bosses having much larger Life pools, and therefore players are allowed to fight them for as long as needed. However, unless managed properly, they certainly can put the player in a situation similar to hitting the enrage timer, such as Malthael spamming his Death Fog.