MArcomage

Lich already does the same thing, but it's not zero cost and does not gain resources for you.

Undead are already powerful attacking cards, are you sure you want to be facing someone who can also discard your cards at will?

This card discards a card from your own hand only, the way I read it.

"Gain resources equal to the cost of the card" the discard card or the new card?

You get the cost of the discarded card.