{T}, Tap an untapped creature you control: Add one mana of any color.

When Thassa's Oracle enters the battlefield, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Each nonland card in your graveyard has escape. The escape cost is equal to the card's mana cost plus exile three other cards from your graveyard. (You may cast cards from your graveyard for their escape cost.) At the beginning of the end step, sacrifice Underworld Breach.

Unholy Heat deals 2 damage to target creature or planeswalker. Delirium — Unholy Heat deals 6 damage instead if there are four or more card types among cards in your graveyard.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Urza's Saga gains "{T}: Add {C}." II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature gets +1/+1 for each artifact you control.'" III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Each opponent can cast spells only any time they could cast a sorcery. +1: Until your next turn, you may cast sorcery spells as though they had flash. −3: Return up to one target artifact, creature, or enchantment to its owner's hand. Draw a card.

Look at the top three cards of your library. Put one of them into your hand, put one of them on the bottom of your library, and exile one of them. You may play the exiled card this turn.