Stuns - Kidney Shot, Deep Freeze, Concussive Blow, Intercept
Uncontrolled Stun (On Proc) - Impact, old Mace Stun, Improved Revenge, weapon procs with stun effects
Roots - Entangling Roots, Frost Nova
Disables - Sap, Polymorph, Gouge, Repentance
Fears - Psychic Scream, Howl of Terror, Blind, Intimidating Shout
Stealth Nonsense - Pounce, Cheap Shot
Disarms - Chimera Shot, Dismantle, old Riposte, Disarm
Silences - Silence, Improved Counterspell, Improved Kick
Physical Avoidance - Dodge, Parry
Diminishing returns in action. This poor bastard will be incapacitated for less and less time with each sap. If I was to do it again, he would be completely unaffected. Chances are he's quite angry about the first three too...
Note that this does not apply to anything that is a debuff otherwise. You can be frostbolt slowed into oblivion as a warrior or rogue, and the only way you'll ever get it off you is by killing them, more or less. Any debuff that lowers your stats or increases your vulnerability has no diminishing returns as well, so don't expect to become immune to Curse of the Elements or Vindication with multiple applications. Your only option to deal with these types is to have them dispelled if that is an option. If you are the user of these skills, keep well in mind that the diminishing returns window is only 15 seconds. If you go 15 seconds without using that skill, it will have full effect. So if you're against a paladin in PvP as a rogue, for instance, after a divine shield is used and he heals to full, likely by the time he's vulnerable again you can open up with another 4 second stun or solid 6 second kidney shot. Monitoring diminishing returns is a key aspect of Arena combat, so you can get the most of your spells and devastate your opponents with a healer fully disabled.
Why is it here?
Besides the above example, there are other reasons diminishing returns was added. Some players simply have too many disables at their disposal to be balanced in PvP, namely Protection Warriors and Rogues. Some have a disable with no cooldown other than the global, such as Polymorph and Fear. Others just have such potency that they have been introduced with the global cooldown well in mind, like the Druid's Cyclone in PvP. From a PvE aspect, if the target is vulnerable to stuns, even in 10 man groups it would be entirely possible to lock a target down for good with well coordinated stuns. When you have such powerful toys available to each class, it's unfortunately necessary to limit their potency on a single target. It's also necessary to, well, preserve the fun of the game.
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