WoW:Cooldown

The term cooldown is defined as a period of wait time before a spell, ability, or item power can be used after a prior spell, ability, or item power. Sometimes referred to by the pseudo-acronym "CD".

For example:

• The time it takes to recharge after a spell has been cast or an ability or item power has started being used. You will not be allowed to cast another spell for the duration of the cooldown period. This is not the cast time, and usually the cast time of a spell or ability is longer than the global cooldown, which means you can begin your next spell immediately after the cast is finished.
• A Hearthstone has a 15 minute cooldown time.

The term cooldown can also refer to an ability with a long cooldown; for example, Save your cooldowns for boss fights.

Shared cooldown

A shared cooldown is when some spell, item or ability prevents usage of certain others while it is cooling down. It effectively applies the same cooldown to all those that it shares cooldown with.

It is important to know if a spell or item has a shared cooldown, since that is much more limiting than an isolated cooldown. This usually means that you must choose wisely which to use, since you cannot use all within a short time period. For instance, many potions share cooldown with other potions, and some of the warrior's abilities share cooldown, as well as hunter traps.

Some abilities have multiple shared cooldowns. For instance the shaman's Earth Elemental Totem can only be cast itself once every 20 minutes, can not be cast within 2 minutes of using a Fire Elemental Totem, and triggers a 1 second global cooldown.

Warrior stance changes also fall under the shared cooldown category. Switching stances as a warrior prevents switching to another stance for 1 second but does not prevent the user of other abilities.

Global cooldown

A global or universal cooldown, frequently shortened to "GCD", is the cooldown which starts every time you start to cast a spell, and it affects all of your class spells. There are exceptions to this, however, as noted below. The basic rule of thumb is that if the spell affects the casting of the next spell, it will not activate the global cooldown.

If the spell has a casting time less than the global cooldown (or instant cast), you generally have to wait the remainder of the global cooldown. If a spell with casting time is interrupted before it has finished casting, the global cooldown will be canceled, meaning you can start casting a new one immediately.

The global cooldown is generally 1.5 seconds for all classes except rogues, Cat Form druids, and Death Knights, whose abilities are mostly one second global cooldown(reduced to 0.5 in UP). Shaman totems also only trigger a one second global cooldown as well as warlock curses with Amplify Curse. The global cooldown affects the wait for the next ability, so using an item or ability with the standard 1.5 second cooldown will require waiting that long before a 1 second global cooldown ability can be used.

Cooldown and usage theory

The cooldown determines how often something (spell, ability, or item) may be used. Specifically, it has an inverse relationship to how many times per fight it may be used.

For example, a druid should never use Rebirth in the post-encounter resurrection.

Here's a rough guide to help with when to burn a cooldown:

Cooldown length		When usable
1.5 sec	GCD	Spammable at will
10 sec	very short	Used as part of a rotation
90 sec	common	Usable often
3 min	common	Usable each battle, sometimes several times during a boss fight
10 min	mildly long	Usable on most tough miniboss fights
30+ min	long	Usable at calculated times and emergencies

Item cooldowns

Items with cooldowns are simply items that have limit on how often you can use them.

For example Major Healing Potion has a 2 minute cooldown, so it can be used just once every 2 minutes. The average cooldown is 2 or 5 minutes, but they range from 10 seconds to 3 hours (like Signet of Expertise) to 3 days at the longest. These items can be equipped in a variety of slots or used from the backpack.

Internal cooldowns

An internal cooldown (or ICD) is the cooldown on several abilities usually found on items. It exists as a regulator to prevent specific chance-to-proc abilities from being active at all times. One example is \Pendulum of Telluric Currents which has a 10% chance to proc and a 45 internal cooldown. When it does proc, there will be 45 seconds before it can do so again. Internal cooldowns vary in duration, but the most common is 45 seconds as with the Pendulum of Telluric Currents.

Internal cooldowns are often hard to perceive and measure. This is because the description of the item which holds the ability rarely tells if there is any cooldown on the ability, nor how long any possible cooldown is. As a result, internal cooldowns are often mentioned as "hidden cooldowns". Because of this, the cooldown of an item's ability is usually discovered via player testing in-game. It is important to know the internal cooldown of an item's ability since it highly affects how powerful the item is. One example is Darkmoon Card: Greatness. It has a 35% chance to proc, a 15 seconds duration and a 45 seconds internal cooldown. If there were no cooldown, players would be able to refresh the duration via procs over and over, enjoying a nearly permanent effect from this item. Applying the cooldown will reduce the time the effect is active to 33% possible uptime (as 15 is 33% of 45), which in comparison reduces the item's performance by almost 70%.

Global Cooldown vs. other Cooldowns

An important consideration for analysis has to do with when a given cooldown begins counting. Global Cooldowns are singularly unique in that they are counted by the World of Warcraft Interface, while all of the other cooldowns are managed by the server. Overall, this doesn't seem important except when playing on a machine with medium to high latency or when measuring interface lag.

Activation Sequence of Events

1. Player activates an ability
2. Global Cooldown activates and begins counting immediately
3. Server receives request (modified by network latency)
4. Ability begins casting
5. Ability finishes casting
6. Ability Cooldown activates and begins counting.

This distinction has particular application when accounting for play techniques. For instance, Global Cooldowns are not a factor when performing latency compensation as the User Interface will not allow activation if a Global Cooldown is active. In contrast, during lag spikes, one may activate multiple abilities as long as Global Cooldown rules are followed. The result during these situations is a multiple seemingly simultaneous spell completions.