Magical Stone Excavation

[HorusMaster]

Discard two cards: Add one spell card from your graveyard to your hand.

I'm assuming that this is considered a cost and as such, not able to use with Dark World monsters for their effect?

 

[SPK]

I would assume so as well, given the structure of the statement, it does appear to be a cost, not an effect of the card.

 

[Jathro]

You both are correct... unfortunately.