Diminshing Returns

From wow.incgamers.com

In order to make PvP fighting as interactive and entertaining as possible, the game have built-in limits on how much you can limit other players ability to do things in a given combat. These limits are called "Diminshing Returns", and just means that if you use multiple "control" or "slowing" spells/abilities on a specific player in a short amount of time, some of them will have less or no effect.

The idea is that if a player recives several control or slowing effects within a 15 second time, they will have lesser effect, or no effect. The first spell or ability used on a player for every 15 seconds will have the full effect (if not resisted). The second spell or ability of the same type used on the same player within 15 seconds of the first effect wearing off will have it's duration reduced by 50%. The third's duration will be reduced by 75% and the player will be immune to the fourth casting. In other words, a player will recive the full effect of a spell if he have been unaffected by that effect for the previous 15 seconds.

These types of spell effects have Diminishing Returns:

• Charm
• Fear
• Stun
• Slowing
• Immobilising

There is a few exceptions to these, in cases where abilities or spells are randomly applied, they rarely contribute to Diminishing Returns (like Seal of Justice). Generally, all spells or abilities that produce one of the effects above will be subject to Diminishing Returns if it is manually used by the player. It is the effect that is important, so some items that produce similar spell effects will also be included.