Do I need to hatch him to get the rewards? I managed to save up some orbs to get him (and later rank-up Gortak), but I don't have enough time to hatch him.
The game says I need to complete the floors, there's nothing about hatching him.

Also he gives no points towards the Legendary Overlords challenge and I want to get the 1500 points chest (I might be able to get it, thanks to the monsters in my storage).

You just need to beat the floors, and after the dungeon event ends you should be rewarded.

@MonstrousManiac are you sure this is correct?

@keki14 Should be the case.

If you read the Nercomancer's Blessing pop-up, it says beat the floors, not craft/hatch.

@Ian-Dunn yeah, I know there's nothing about hatching, but some people said I need to hatch him, just to be sure. But I don't want to, because of the event.

@keki14 Well they haven't read the official post now have they?