Not sure if it still does stack post-Scalebreaker, but it certainly used to stack back when it was still called mutagen/rapid regen.
While zergsurfing, I would frequently have quite a few mutagens + rapid regens on me, in addition to my own mutagen.
Edit: logically, it SHOULD stack, considering that 2 healers is the norm for many trials... but since this is ZOS we're talking about, logic is clearly overrated
I’m pretty sure 3 stack, same as echoing vigor. Doesn’t matter who casts it.
Edited by Iskiab on August 24, 2019 7:20PM
Looking for any guildies I used to play with:
Havoc Warhammer - Alair
LoC EQ2 - Mayi and Iskiab
PRX and Tabula Rasa - Rift - Iskiab
Or anyone else I used to play games with in guilds I’ve forgotten