MArcomage

This card is very funny, but rarely used. stock +10 is too much in my opinion.
what about stock +5, or stock based on discarded card's rarity?

Yes, it seems very underused. Since we now have statistics section we can check every card's usage ;-). I propose stock +6 instead of +10.

Rarity based seems a fun idea. Something like 1/3/8?

I also like the rarity-based idea.