I have defeated Hagatha! Took me three attempts to get her but overall it felt much easier than the four classes you need to win with before her.
The mechanic of the fight is kind of cool where you get to switch through all of the other classes and pick a new passive when you first switch to each class. You only get to switch once and timing when to switch seemed very important.
When I finally won it felt more like luck than skill. I got ahead on the board in the later part of the game and didn't get murdered by RNG.
Overall was a very cool event. I like what they did with this round to help spice things up from the original dungeon run and hope they continue to make new dungeon runs in the future.