Greg makes a comeback in the form of Greg's Reversed Fate tactical rifle in The First Descendant, whose unique ability has been revised in Update 1.0.5.
GREG'S REVERSED FATE MAY BE THE NEW BEST WEAPON BUILD | The First Descendant DPS Guide
The Shaping Destiny effect now has a chance to activate Bombardment, dealing Burn to any enemy instead of just fully shielded enemies. This means you can unleash the power of orbital attacks, just like Greg and his clones do almost every day.
This is the best Greg's Reversed Fate build in The First Descendant.
Greg's Reversed Fate has great base stats for both Firearm Critical Hit builds and Weak Point Damage builds. For general use, focus on Firearm Critical Hit and Firearm ATK for more consistent damage. You can build Weak Point Damage for boss fights, but that's up to you.