Expiration rate

The expiration rate of a temporary effect describes how fast or slow time progresses for that effect relative to real time.

Ordinarily, the expiration rate of a temporary effect is equivalent to real time – that is, one second of temporary effect duration lasts one actual second – however, there are modifiers that can increase or decrease it. Modifiers that cause a temporary effect to decrease the expiration rate of that effect, thereby making it last longer. Similarly, modifiers that cause it to increase its expiration rate, making it last a shorter period of time.

Mechanics
Despite changing the total time that temporary effects last, it does not increase or decrease the duration of that temporary effect. For most characters this difference does not matter, because the main goal is an overall longer or shorter time for the game mechanic. The difference only matters for benefits and/or downsides that only affect expiration rate or duration. For example:
 * Vaal skills with duration buffs/auras, like and  will gain soul gain prevention time from  modifiers, but not from those that affect expiration rate. Therefore having these skills expire slower on you will result in them being active more often than increased duration would.

Temporary effects that can possibly be affected by expiration rate include buffs, debuffs, curses, flasks, and temporary auras. Temporary effects that are not affected by expiration rate include rage and focus.

Gems



 * phantasm alternative quality

Buffs



 * Rupture

Ultimatum league introduced a trials of chaos. These trials can have an option that makes buffs expire three times faster. This does not affect all temporary effects listed above, only buffs.

Items

 * grants Modifier:HasteDebuffsExpireFaster