A huge prize is a serialized card with a limited number of printings
For decks with three or more colors, where you might only be able to afford a small number of MDFCs since you'll need most of your lands to either be basics (for ramping / tutoring purposes) or tap for multiple colors of mana, the best MDFCs are Bala Ged Recovery (seriously, if you have green mana in your deck, play this card), Valakut Awakening, Hagra Mauling, and Ondu Inversion, along with the mythic cycle, which is almost always good if you can afford another land that only taps for a single color of mana
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If you want to fight delve against a deck that uses it like they use Tarmogoyf, might I suggest Relic of Progenitus
Luffy: Introduces a powerful new Leader card with multicolor deck-building potential
Add Card Border Add a card border to complete the Pokemon card look