Here be dragons! Bugged
NVM – figured it out. The “kill a world boss” resets every day, and, from what I can tell, Wurm/Behe/Maw/Covington/Fire Shaman do not count. Has to be a dragon.
Behe counted for me once. I know cause I was surprised to see the daily achievement pop up for it, but it did. On the following day, it didn’t. So might’ve been a temporary anomaly/bug. Shatterer or Jormag always count, so if you (like me) don’t like fighting Tequatl, you can get your daily on either one of these.
Yeah, finished it off. Behe, maw, covington, fire shaman, fire elemental, golem didn’t count. Shatterer did. Ergo, had to be a dragon.
The boss that counts changes. For example today’s is “Participate in the Tequatl encounter 1 times.”. On other days it has something " or any of the other world bosses".