Roaming Ghostlight is a brand-new card that you will want to hoard; draft as many copies as you possibly can.
It's very similar in effect to Chillbringer from Ravnica Allegiance, which was a real powerhouse in that limited season.
Play Roaming Ghostlight and bounce the biggest creature on the opponent's side of the table, forcing them to replay it again during the next turn. They will spend all their mana while you attack in the air. It's a simple strategy that has won many limited games in the past.