He seems to sometimes be going incredibly long periods without casting it, something I can’t find in any video or recall in my own experience.
00:00:55.502 Kel’Thuzad casts Frost Blast on Chewy
00:02:32.975 Kel’Thuzad casts Frost Blast on Soildsra
A full 1m37s without casting his ability that clearly has a 25 second cooldown since other times he’s casting it every 25 seconds.
I suspect it’s something to do with batching so he’s missing a cast and resetting his timer somehow.
Also less extreme examples
00:00:34.982 Kel’Thuzad Frost Blast Kiwiandapple 1818
00:01:45.867 Kel’Thuzad Frost Blast Kiwiandapple 1817
00:01:48.692 Kel’Thuzad Frost Blast Kiwiandapple 1818
00:03:07.292 Kel’Thuzad Frost Blast Leps 1738