So, I ended up getting the CD Reduction trinket off Galakras today. Having been bugged on the PTR, I figured that Blizzard would have fixed it for live (Or changed to tooltip to reflect any nerf to it). However, as far as I'm aware, Blizzard has never said anything about it and I have never seen a post reporting it bugged prior to this either.
Details: Basically, the tooltip says it should reduce the CD of abilities (The one I am examining currently being Pillar of Frost and the focal point of discussion currently) by 42%. However, it is only reducing it by around 29.5% or so. If the tooltip is correct, then it should reduce Pillar to a 34.8 second CD instead of a 42.3 second CD.
Last edited by Nyanmaru; 2013-09-11 at 12:36 PM.
Reason: Reduced size of headline
No it's not bugged or nerfed. (yes it was nerfed first but it's not similar to your issue). It's just smart use of wow development team trolling mechanics. I don't see the reason why they did this either.. You're not the first came up with this question and many people will be confused and many more topics will show up everywhere.
It does not say "Details: Basically, the tooltip says it should reduce the CD of abilities (The one I am examining currently being Pillar of Frost and the focal point of discussion currently) by 42%."
it says it reduces your cooldown recovery rate by %42, which brings us to your misscalculation. You cannot %42 of your cooldown.
correct math is 1 / 1,42 = 0.704225352.
1 - 0.704225352 = 29.5774647.
It should reduce your cooldown by %29.5774647.
So your observation was right it's %29.5
As the two posts above have said, the perceived issue is because of the difference in the wording.
The trinket increases the cooldown recovery rate, whereas you said it decreased the cooldown. The important words have been italicized.
Picture a pool being filled by a hose. When the pool is full, the cooldown is ready. There are two ways to fill the pool faster: increase how much water you're flowing into the pool, or decrease the total volume of the pool. Increasing the cooldown recovery rate is analogous to increasing the flow rate. Decreasing the cooldown would be analogous to reducing the volume of the pool.