keen cloak
Create a spectral card when this card is destroyed.
This suggestion is simple. Spectral cards are fairly difficult to come by on anything other than ghost deck so any addition that would make them easier to get would benefit a lot of runs.
Since you need to destroy the card with the seal (eg. with hanged man, glass break, trading card, etc.) to get a spectral card, you'll only be able to get one consumable per card. This contrasts with blue/purple seals which can be reused to give multiples of their respective consumables.
This addition should make spectral cards easier and more consistent to get whilst still keeping them rare and special.
lavish bough
sonic mica
opal sky