Phase 4 of World of Warcraft Classic Season of Discovery has added more features, including opening up instanced encounters with Lord Kazzak and Azuregos.
Both of these world bosses are now live in reimagined form as these new instance encounters that you can take on with up to 40 players. There is a good degree of flexibility, however, since the encounters are tuned as 20 player content. Jumping in as a pickup group with 40 players will work, but what this also means is that if you jump in with 20 players you will maximize the rewards you could possibly get.
So there are some trade-offs between let's jump in and do this and let's do this in half the size group, organize it well, maintain strategies, and go in there to get the best possible loot.
Season of Discovery Phase 4 has been rolling out this content over time and there's still more to come. Next week on July 25th, another reimagined feature is on the way. If you think you know Molten Core, that familiarity will help, but things will be different when that goes live. This will now be a 20 player dungeon featuring 10 classic bosses, redesigned Tier 1 sets, and updated loot. Onyxia will be adjusted to accommodate 40 players or fewer.
Blizzard promises that there is another surprise coming to this raid dungeon and they aren't telling until it's out globally on July 25th at 1:00 p.m. PDT.
The more risk and more reward also applies here, since there is a new mechanic that allows for variable difficulty and player choices. If you want to you can take on this challenge at a higher difficulty to earn more rewards for a victory.