Obsillus, the Eternal Forge

Whenever an artifact enters the battlefield under your control, you may pay {r}{r}{g}. If you do, Obsillus, the Eternal Forge deals X damage to target player or creature, where X is the number
of artifacts you control.
{r}{r}{g}: Destroy target artifact. At the beginning of the next upkeep, return that artifact to the battlefield under your control.