Theres a strong identity to not just the set as a whole, but the cards within it too
The downside is that since Marvin is a colorless creature, running him as your commander severely limits the cards you have access to with strong activated abilities
For Blue, Fading Hope, Rona's Vortex and Make Disappear are solid answers
For example, if you control The Ozolith ("Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.") when Zack Fair's last ability resolves, you'll put the appropriate number of each kind of counter onto both The Ozolith and the target creature.
Why go for Glasspool Mimic over any of the other clone cards
Inventors' Fair is already an above-average card when it comes to pricing, usually gravitating around the $10 and above range