World of Warcraft at Ten Ton Hammer

If you played World of Warcraft in the good ol’ beta years, you know all about how broken it was at one point, especially in PvP.  Thousands of mages were rolled simply because...

If you played World of Warcraft in the good ol’ beta years, you know all about how broken it was at one point, especially in PvP.  Thousands of mages were rolled simply because Polymorph lasted a minute on players, and could be refreshed no problem.   It was a time of terror, and many fled to the hills and protected settlements to avoid wandering around as a sheep for hours on end if the mage felt like it.  It was time for a new mechanic to be introduced.  Welcome to Diminishing Returns, the term for repeated applications of an ability type that has a shorter duration when applied consecutively. 

What does it apply to? 

Diminishing Returns in general applies to anything that makes you lose control over your character.  So here's a brief list of examples that will grow weaker if slammed into someone repeatedly, be it monster or opposing player. 

Stuns - Kidney Shot, Cheap Shot, Deep Freeze, Concussive Blow, Intercept 
Uncontrolled Stun (On Proc) - Impact
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?