https://www.wowhead.com/item=230011/lilkazs-hilt

Thanks for the reminder! I've been looking into the pet, and it seems there are a few problems:

The drop rate may have been increased drastically, at least on the first attempt of the day. There isn't enough data to say for sure, but if true then it might not be worth adding the pet to the database. Time will tell if that's indeed the case.

Regardless, tracking Kazzak's loot doesn't seem to be possible currently. At least I was unable to get attempts to register reliably. The game simply pushes a generic loot toast, which Rarity only managed to detect once in three attempts.

Finally, the anniversary event itself must be implemented as a "holiday" in Rarity. The code for this works by scanning the ingame calendar for texture paths, with a backwards-compatible translation between those and Blizzard's more recent file data IDs. The anniversary event doesn't have an equivalent in the old system, so detecting it requires some changes here.

I've made an effort to update the holiday detection, but I'll wait for more data before doing anything else.