Sidequest: Play Blitzball seems quite good, giving a nice power boost upfront and eventually transforming into quite a powerful equipment, World Champion, Celestial Weapon
Act of Authority passes itself to an opponent after its use, but its also the best noncreature removal spell that also benefits your commander
If you're setting up Sac payoffs, the card is worth it alone for the cost-free, Instant-speed Sacrifice ability
If an opponent clones it or has free counterspells
Moana, Huey, Scrooge, and Gyro are heavily situational, relying on either locations, items, or synergies with specific cards to find value
Some cards like Enter the Infinite and Finale of Revelation are pretty much designed to close out a match