What happens with 100% reduction of control impairing effects?

Does this grant immunity to status effects such as stun, charm, freeze, fear etc? Also, is this achievable?

Solution 1:

I did it once with my monk for the fun of it, and sold the equipment later on.

The gear had approx. 81% reduction in total, plus the Perseverance rune on my Mantra of Evasion.

What happens? The frozen/jailed animation kicks in for a moment, and you are free a millisecond after that. Although, this was pre 1.03 patch. I don't know if they changed this behaviour afterwards.

Solution 2:

Note: This is mainly to point out post-1.0.3 changes which bora didn't cover in his post; I haven't done any testing on 100% CC reduction - hopefully bora or someone else gives us more details.

From the patch 1.0.3 notes:

Crowd Control Reduction from items and skills will now reduce the percentage value of Slow, Chill, and Attack Speed debuffs rather than reducing how long the debuff lasts

For example: previously, if you were debuffed by a 60% slow that lasted for 2 seconds while wearing gear that provides 20% Crowd Control Reduction, your movement speed would be reduced by 60%, but only for 1.6 seconds. Now, the same amount of Crowd Control Reduction will reduce the Slow effect to 48%, but the effect will remain for the full 2 second duration.

As they specifically mention chilled, I imagine it works as described for Frozen - no idea if Jailed also means you get to drag along the jail at half speed, if you have 50% reduction.