MArcomage

I understand the math behind it, but is it supposed to set each player's stock to those values, or is it supposed to add to (and if negative, reduce) current stock by those values? Right now it looks like the former, but I get the feeling it is supposed to be the latter since you can't have negative total stock.

Y, it should add/reduce the stock. I hope it is now better formed

An interesting idea, but it's a bit weak isn't it?
In most cases you have (nearly) the same number of uncommon/rares on hand...
I would change it to common or set the uncommon and rare stock gaining/loosing much higher...

you could alter it and add the number of keywords in hand (like Rainbow Dragon) in addition to the rarity of the cards in hand

I increased the Stock gain for rares and uncommons.
Your Idea, Lord Ornlu is nice too, i think i will create a alternative Form for Keywords.