This bug applies to Holy Priest using Guardian Angel talent with Ineffable Truth corruption. There may be other classes with hard set CD value changes this affects.
When Guardian Spirit expires without being consumed, Guardian Angel sets the CD to 60 seconds. This is not a reduction, it is a “set value”. This can happen during Ineffable Truth buff/proc (GS and IT both are 10 seconds, so IT must proc after GS cast). When IT expires, the CD is increased again - (Remaining CD) * (1 + Ineffable % / 100) - which is the normal behavior of IT.
With the talent you expect no more than a 60 sec CD if GS is not consumed. But if the Guardian Angel talent is applied during Ineffable Truth buff you end up with over a 60 second CD on Guardian Spirit once IT expires.
This gets WORSE with more Ineffable %.
I am running 60% IT and end up with about 1m30s CD if IT finishes after Guardian Angel talent sets the 60s CD.
A more extreme example is running 300% IT (6x Ineffable II):
Cast Guardian Spirit
CD: 180s
5 seconds pass
CD: 175s
Ineffable Procs
CD: 43.75s (300% reduction)
5 seconds pass
CD: 38.75s
Guardian Spirit expires
CD: 60s (Guardian Angel talent “reduces” to 60 seconds)
5 seconds pass
CD: 55s
Ineffable expires
CD: 220s (undo 300% reduction)
We are now 40s over the original 180s CD of Guardian Spirit CD and 15 seconds has passed.
Even if Guardian Angel doesnt increase the CD from 38.75s to 60s and inflate the CD over the original (it could be a min(current, 60) function), it still negates the Guardian Angel talent completely and you end up with a 155 second CD on GS instead of 60 at 300%. You need about +200% ineffable to be in this category where the CD becomes less than 60 seconds with Ineffable active. I dont have enough IT myself to test what really happens in this situation.
Other builds with < 200% IT still have reduced benefit from Guardian Angel.
If Guardian Angel talent activates during Ineffable, the 60 seconds should be scaled to match the Ineffable buff ( 60 / (1 + Ineffable % / 100) )