Delve

Delve is a cost-reduction keyword ability. It was introduced in Future Sight.

From the ()

Cards with Delve

Card	Set	Comment
Death Rattle	Future Sight
Logic Knot	Future Sight
Tombstalker	Future Sight	The only creature with delve

Rulings

• Delve can't reduce the colored portion of a spell's cost.
• When using delve, a player can remove a number of cards in his or her graveyard that exceeds the generic mana cost of the spell. Doing so will reduce the generic mana cost of the spell to 0, though the colored mana cost of the spell will still have to be paid.
• While playing a spell with delve, you can sacrifice a permanent as part of a mana ability, then remove that card from your graveyard as part of delve. So a Blood Pet, for example, can be used twice to help play a delve spell. The same is true if the spell has an additional cost such as "sacrifice a permanent" or "discard a card."