I went to farm Jabermagwai for an Anointed Maddening Tracker and ended up with 15 of these after about 30 minutes.
It seems like this is the only Epic Tier grenade it drops. Could this be a one off or is there are chance there are dedicated sources for epics as well.
FYI, I’ve save/quit, left the map, and changed the mayhem modifier. It’s still mainly dropping this grenade.