Currently 15% physical res with one skill point.
Make it scale from 3 to 15%, ultimate at 20%.
But it needs something more, just compare it to Trance of Convalesncence, 15% damage absorption, plus mana- and health regeneration.
I suggest fire retaliation, 10/75/100, has to be tested, then also reduce the cooldown, it's currently 90 seconds. Drop it maybe to 60 seconds.
Maybe add flat defensive ability bonus there, 10/50/75.