I never knew Second Wind could critical. It never has from any of my limited uses with it (Mantra replaced it on my cross-skill hotbar) but I find Bloodbath has a few interesting uses. The obvious is how it stacks with healing abilities like Mercy Stroke, Storm's Path, and Inner Beast (and also gives you healing on multi-hit attacks per hit such as Overpower and Steel Cyclone) - but it also works off of things like cannons. Such as the ones used in Praetorium (or was it Castrum?), Stone Vigil Hard Mode and Steps of Faith.