Sidequest: Play Blitzball seems quite good, giving a nice power boost upfront and eventually transforming into quite a powerful equipment, World Champion, Celestial Weapon
Some cards like Enter the Infinite and Finale of Revelation are pretty much designed to close out a match
Act of Authority passes itself to an opponent after its use, but its also the best noncreature removal spell that also benefits your commander
All of these cards are over-costed by one mana because you get the Embalm benefit
Moana, Huey, Scrooge, and Gyro are heavily situational, relying on either locations, items, or synergies with specific cards to find value