2021-06-18 : Although Urza's Saga has the Urza's land type, it doesn't interact with Urza's Tower, Urza's Mine, or Urza's Power Plant.

2021-06-18 : Even though Urza's Saga is a land, it is also still a Saga, and it will be sacrificed after its last chapter ability resolves.

2021-06-18 : If Urza's Saga loses all of its chapter abilities but is still a Saga, perhaps due to a card like Blood Moon, it will immediately be sacrificed.

2021-06-18 : Urza's Saga gains an ability from its first and second chapters. It keeps those abilities for as long as it's on the battlefield.

2021-06-18 : Urza's Saga is a land, so it can only be played as a land. It cannot be cast as a spell.

2021-06-18 : While resolving the chapter III ability, you can find only a card with actual mana cost {0} or {1}, not mana value 0 or 1. For example, you couldn't find a card with mana cost {U} or one with mana cost {X}.