It doesnt produce any mana and it instead gives an ability to every creature on the board that causes them to be destroyed unless the person controlling them keeps paying mana to prevent this from happening
I am just playing Cut Down and Withering Torment to help me stabilize, and Withering Torment can be used in a pinch to save yourself from an expiring Archfiend or Pact stuck on your side of the board, or to remove an already-donated Greed's Gambit to have your opponent sac 3, lose 6 life, and discard 3 cards
Power-doubling effects like Unleash Fury, Two-Handed Axe, and Calamity Bearer pair wonderfully with Double Strike-outlets like Duelist's Heritage, Embercleave, and Arashin Foremost, resulting in a quadruple damage per swing
If Teferi were around today, he would be similar to Jace Beleren in terms of in-game reference, power, and influence on the game