Just got Smiddi to level 99. The Heal unlock is pretty nice. Contrary to what several sources would say, her 99 unlock is NOT for her. It actually buffs the lunar heal other spell we can use. Smiddi herself does not take damage when casting heal other, at least if she does no damage splat appears and she seems able to cast it multiple times and never eat. I didn't test it extensively but I was able to take both of us from each being around 160hp to him fully healed with 990 hp and I had 224 hp in a minute or two. For the test I was the only one with the upgrade.