Magmatic Sinkhole

Text:

Delve (Each card you exile from your graveyard while casting this spell pays for .)
Magmatic Sinkhole deals 5 damage to target creature or planeswalker.

Rulings:

• 6/14/2019 When calculating a spell’s total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Delve applies after the total cost is calculated. Delve doesn’t change a spell’s mana cost or converted mana cost.
• 6/14/2019 You can exile cards to pay for only generic mana of the spell with delve.