This is borderline useless in a lifestall. The idea behind a lifestall is to heal more than the enemy can deal damage, right? The failure of the lifestall is that once damage exceeds 100, it is doomed. This potentially allows you to heal more, but the increased potential of the enemy to use this to deal more damage is generally greater than your increased potential to heal. And, once that damage reaches 100...
Monolife rush I can see the potential for, but I would still rather have straight up adrenafrogs.
Funnily enough, the deck I see the most potential for with this is a firestall. Firestall has no problem killing whatever extra creatures this draws, heal is irrelevant because stall, and upgraded mark means Fahrenheit/Firebolt craaazy strong. 10 heal isn't much when 75 quanta Fahrenheit does 20 damage a turn, and then firebolt OTK becomes easy. Many firestalls splash in light for healing. They can splash this in instead.
Its also powerful, but so double edged it deserves a cost reduction.