Abilities that require you to tap the permanent theyre on certainly feel like they can only be used once per turn, but you can use the ability again if another ability untaps it
Courser of KruphixCourser of Kruphix (23,242 Inclusions, 7% of 327,420 Decks) Speaking of cards that have recently gotten shout-outs from new sets, here's Courser of KruphixCourser of Kruphix
Overcosted removal is still overcosted, even if you paint a different picture in the art box
Despite Grixis Shadow being currently maybe the strongest deck in the format (thanks to Lurrus obviously) I think Deaths Shadow is not the correct way how you want to approach your tempo deck in the future
You can also make more Powerstone tokens with Fallaji Excavation, Argothian Opportunist and Hall of Tagsin
Honestly, this maybe should be a demon typal deck, assuming you can slot in enough sacrifice fodder to cheat in your demons