Halcyon, Thran Capital

When Halcyon, Thran Capital enters the battlefield, create a tapped Powerstone token.
(It's an artifact with "{t}: Add {c}. This mana
can't be spent to cast a nonartifact spell.")
At the beginning of your upkeep, sacrifice another historic permanent. If you can't, sacrifice Halcyon. (Artifacts, legendaries, and Sagas are historic.)
Tap an untapped artifact you control:
Add {c}.