Suggestion: Sacrifice should be a bit more of a sacrifice
This will probably be an unpopular suggestion, but before anyone can slap me with the troll badge, I am completely sincere in this request.
It seems like the healing spell "Sacrifice" is a bit of a misnomer. Sure, it takes HP to cast, and yes, if I'm low on HP myself I won't be able to save my skin or anyone else's. But in a typical battle with a team of players, I rarely get so low in my HP as that. I'd like to see Sacrifice spells either not heal the caster at all, or impose a damage over time on them that slowly drains away some of their HP for as long as the healing over time on others is active. I think it would make for a more interesting dynamic, and make the spell's name and description more meaningful.