if I have a card such as Skaab goliath that I want to cast that has an ADDITIONAL cost of "exile two creature cards from your graveyard" but I don't have any creatures in my graveyard can I still cast it even though I don't have the resources to pay for its additional cost?
If the additional cost is required you cannot cast it without paying the required cost
{Skaab Goliath}
Yea but how do you specify if an additional cost is required?
Unless it says "you may" assume it's nessessary.