Blizz either take this off the same end cap as Undergrowth or Make it a 100% chance. It really does suck that in raid its our best ability and it works roughly 25% of the time over a boss fight.
Or even worse, in your time of need in M+ it doesnt go off until dmg is relatively low.
I think Putting the 2 on separate end caps again would help a lot with M+ panic mode and will be a useful talent in raids without making the druids healing OP.