We Heal As One refreshing boons
My regen seemed to max out at around 1m 40s when I was trying it out. The first few times using heal as one, the uptimes doubled, but then once it reached that point they wouldnt go any higher.
I have no idea haow its supposed to work, just giving a comparrison for the curious.
Not a bug working as intended and I am pretty sure that duration stacking boons get an application threshold.