Dig Through Time
Instant
Delve (Each card you exile from your graveyard while casting this spell pays for 
.)
Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in any order.
Ryan Yee
Magic Online Promos (PRM)
• #99973Rulings
You can exile cards to pay only for generic mana, and you can't exile more cards than the generic mana requirement of a spell with delve. For example, you can't exile more than seven cards from your graveyard to cast Treasure Cruise unless an effect has increased its cost.
(wotc • 2021-03-19)
Delve doesn't change a spell's mana cost or mana value. For example, Treasure Cruise's mana value is 8 even if you exiled three cards to cast it.
(wotc • 2021-03-19)
Because delve isn't an alternative cost, it can be used in conjunction with alternative costs, such as flashback. It can also be used to pay for additional costs that include generic mana.
(wotc • 2021-03-19)
Printings
Rulings
You can exile cards to pay only for generic mana, and you can't exile more cards than the generic mana requirement of a spell with delve. For example, you can't exile more than seven cards from your graveyard to cast Treasure Cruise unless an effect has increased its cost.
(wotc • 2021-03-19)
Delve doesn't change a spell's mana cost or mana value. For example, Treasure Cruise's mana value is 8 even if you exiled three cards to cast it.
(wotc • 2021-03-19)
Because delve isn't an alternative cost, it can be used in conjunction with alternative costs, such as flashback. It can also be used to pay for additional costs that include generic mana.
(wotc • 2021-03-19)