it is, actually. xp brews have a chance of dropping from all of the artifact dungeons up through stage 15. they have a pretty low drop rate (~10% on stage 1 and down to 7.25% on stage 15) so you don't see them that often, but they are a possible reward.

Ah okay, I thought it was only the potion keeps that drop xp brews.

I just took a clan quest to put 10 debuffs on the ice golem at stage 15 or above. I wouldn't normally run a stage that low, so I guess thats why I was surprised.

Thanks :)