wow, i really like this. as lord_midnight said, life already has a growth creature in forest spirit/specter, but not one that finally gives rustler a real purpose. i'd like to see it used in multiples, but as it drains all your quanta this makes it more difficult. perhaps instead of draining quanta you could have it do something like:
Natural Wrath - 3 
: Protector gains +1/+1 for each 5 quanta. Protector is destroyed at end of turn.
The destruction part would still be detrimental against some decks, but as a last minute attack, this edit makes it sound much more... intriguing?
The way you word it makes it sound like a SPELL, rather than a creature (I mean, it's the Life equivalent of Spark with an adjustable attack bar depending on your
quanta). If the Protector is going to be destroyed after its usage, why not just make it a one-time use card (or a permanent that you can trigger), rather than a full-blown creature that can help grant a few skeletons (Graveyard/Boneyard) and Bone Walls.
If it's not a one-time use card, I'd say that it'd be cool if its attack
decreases overtime, as in gain +X/+X (with X being a # of quanta of
depending on the ratio) at the beginning, but decreased gradually until it hit 0 - this way,
it's the opposite of Forest Specter. Initially, it gives a huge wallop if used correctly (and a good finisher), and over time, will continue attacking, until it runs out of steam.
Combine either of these ideas though with
Adrenaline (since it's a creature still), and you'll get a one-shot card though. =(
