A 3/5 flier for 4 isn't at all a bad start
($150) The Modern Masters and Double Masters prints of Mox Opal can be found for about $150, while the Kaladesh Inventions print can cost more than $500
It was even one of the best cards in early Historic Izzet Phoenix lists because spells like Curious Obsession and cheap cantrips helped it grow fast while dodging damage-based removal
(9/20/2024) If a face-down creature loses its abilities, it can't be turned face up with a disguise or morph ability because it will no longer have that ability (or the associated cost) once face up
Either burn their last few life points with Rubble Rouser and Thunderdrum Soloist, or use Duel Tactics, flyers and Lorehold charm to go around, over or through their blocks for the deathblow
Turn it face up any time for its morph cost.) When this creature is turned face up, return all other tapped creatures to their owners' hands