Kel'Thuzad's ability use on PTR

#1 - Nov. 5, 2020, 3:06 a.m.
Blizzard Post

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

00:01:48.692 Kel’Thuzad Frost Blast Kiwiandapple 1818
00:03:07.292 Kel’Thuzad Frost Blast Leps 1738

If we look at something like this

Frost blast at


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#15 - Dec. 2, 2020, 11:04 p.m.
Blizzard Post

The question raised in threads like this one have been on our minds a lot as we’ve been testing on the PTR the last couple of months.

So let’s take a moment before Naxxramas releases tomorrow and talk about how boss abilities work in WoW Classic and Original WoW.

Why doesn’t Kel’Thuzad use abilities on strict timers?

The simple answer is, for the most part, that’s not how boss abilities work in World of Warcraft (Classic and Original). Bosses and other creatures are rarely set up to have exact timers for spells and ability usage. They often make decisions which were set up to be somewhat unpredictable. Multiple spells or abilities can be available to the boss, and they will deliberately evaluate what to do following their last spell cast.

Additionally, some bosses have abilities that share cooldowns in some way, similar to how players can’t activate two empowering on-use trinkets at the same time. This means that if a boss uses a significant ability, some of the other abilities that boss has may not be usable for a short period of time.

There are, of course, exceptions. Not all mechanics encountered in combat are being controlled by the same logic, and spells can have different shared cooldown categories, or they can be excluded from this restriction altogether.

In either case, these are typically purposeful design decisions, and the general intention was to prevent a boss from unloading all of its most impactful abilities within moments of each other. In the case of Kel’thuzad, we see it currently working correctly.

For comparison, here are a few other examples of encounters that have deliberately unpredictable ability recast timers, the result of which can become quite pronounced as combat time increases (or as combat time decreases, depending on your perspective):

  • Magmadar’s Panic Recast
  • Broodlord Lashlayer’s Blast Wave
  • Gurubashi Bat Rider’s Unstable Concoction
  • Nefarian’s Bellowing Roar

You’ve probably noticed this before with these encounters (or others), and it’s definitely accurate to say that this can and does influence the difficulty of the same encounter–at times wildly–from week to week.

In later versions of World of Warcraft, and with the continued advancement of player knowledge and skill, many foundations of encounter design changed to make randomness less of a factor in encounter difficulty. In WoW Classic however, the behavior of Original WoW has been preserved.

We hope this helps shed some light on this for you. We can’t wait to see you Naxxramas tomorrow. May your Frostbolt Volleys, Deep Breaths, and Bellowing Roars be many and eventful*.

*Or not!