Artifact spells you cast cost

less to cast.
As Aphelios enters the battlefield, you may reveal any number of other artifact cards from your hand. Aphelios enters the battlefield with a +1/+1 counter on it for each card revealed this way.
Whenever another artifact enters the battlefield under your control or another artifact you control leaves the battlefield, you may pay

. If you do, target player loses 3 life and you gain 3 life.