dark energy card pokemon 2020 Darkness Reverse Holo Promo #096/S-P None Number Darkness Energy - SWSH01: Sword

They are great in most kinds of magic but in cube they are near there peak performance

Limited implications Forage is a great mechanic for Limited, because the card is worth something whether you can forage or not

the mono-red ones in Planar Chaos , for example, just used R.) A Artifact (This is for traditional colorless artifacts

Which of the ones you have right now is/are your favorite(s)

This "Graveyard Hoarder" mentality is why Nightmare Shepherd is likely going to be completely overlooked and unexplored by the vast majority of Commander players, which is a shame because it's actually a great card in a few decks