Weakstone's Subjugation 
Enchantment — Aura
Enchant artifact or creature
When this Aura enters, you may pay 
. If you do, tap enchanted permanent.
Enchanted permanent doesn't untap during its controller's untap step.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL