Howling Mine is the grandparent of them all, having seen the light of decks back in Alpha , and it does have an interesting catch that not all later iterations have: You can turn the hugs on and off, as long as you have ways to tap or untap the artifact as needed
Rip it off the top, cast it for its miracle cost, and absolutely decimate someones board and life total
The Cryptolith Rite decks of last Standard would have loved to have access to this card, but finding the home for it right now is much harder
Powerstone tokens say Add one colorless
Of course, if you can pair this card with any number of red mana-ramping spells (a la Seething Song or Battle Hymn) and one-mana cantrips (like Might of the Meek, Ancestral Anger and the like), it truly sings, and it pairs beautifully with many other cards on this list