LE 30 Kairos Fateweaver (Legend)

Each development you control becomes a unit with 2 hit points and **. It still counts as a development.

Q: If the Fateweaver is in play and a development became a unit, what happens to the development-unit when it is destroyed after a combat? Will the card enter the discard pile? or Just return to the status of development?

Thanks for the answer...

It is destroyed and enters the discard pile. Once there, it loses both the development and unit status and becomes again what it originally is.

Correct. Because a unit with 0 HP, or with as much damage as HP on it, is destroyed and goes to it's owner's discard pile.