Heart gem is cool except for a couple of situations. I use it in almost every run, but most of the time, something is missing, and I die before finding it.
It feels bad when I collect a handful manastones and don't find a good damage wand. It also feels bad when I find a good damage wand but haven't saved any manastones. And one time, I had both, but didn't have (and get) any healing. That felt the worst.