MArcomage

Illusion.
If last card was discarded bonus stock based on discarded card rarity (C-9, U-15, R-21)

These stock values are huge! I'd say divide them by three or make those numbers reflect (random?) resources gained rather than stock.

How about 1/3 the cost of the card discarded? That encourages you to discard large (and powerful) cards.

Nah, I like gaining random resources better. Expensive cards don't always deserve the term 'Powerful'. I'd stick to a quantity determined by rarity.