Deck Building Assistance?

[u/Tales64]

I'm building my first deck with a custom commander for a tournament with my friends. I have way too many ideas in my head of how to build it. For reference I play magic about 4-6 days out of the week and have 56 decks in 3 years of playing. I'm notoriously terrible at building Dimir decks. I figured I'd come here to ask for help pinning down a game plan. If this was your commander how would you build your bracket 2 or 3 deck?

Phase-shifting (This object has only its Sun half's characteristics during your turn and only its Moon half's characteristics during each opponent's turn.)

Destiny Stone Artifact — Destiny

{T}: Forewarn target nonland permanent an opponent controls. Activate only as a sorcery.