seems a bit weak;
best targets for quantaefficience should be ball lightning and voodoodoll. This is identical in cost to improved heal/holy flash and a permanent with
upkeep: generate up to 1 death effect each turn.
Rather extreme buff: Also draws a card upon use.
Other strengths that I did not take into account: Highest possible heal from 1 card: Golden dragon heals 36 (upped); upped wyrm can heal 25 with ability (if it uses current attack). Singularities.
Helps dealing with (self-) flooded board (bone yard aflatoxin), but fallen elf or immolation would be better for that most of the time.
I also forgot about basilisk blood which is 1 cheaper than heal.