So let me throw this out there... Base item - Healing Barrel. Set it up in your base, you can break it for SC. You could have every barrel in the game as a base item - the only stipulation behind them is they cannot be placed in pre-set points. This basically makes them unavailable during any lair battles.
They've staunchly opposed adding things to help build supercharge outside of instances. In their words (paraphrased), SC as a game mechanic is meant to be built up during the course of play. I do like the idea of having different kinds of barrels, or crystals which do the same, during lair battles. Freezing, adding a DoT, etc would make it more dynamic.