Going straight from 3 mana to 6 the next turn after you play a land lets you rocket out some terrifying beaters like Hellkite Tyrant and Ancient Copper dragon quite early, and you can run blacks cheap graveyard tutoring like Buried Alive or Entomb to gain easy access to a variety of threats
Miasma Demon Four generic, two black creature Demon 5/4 Uncommon Flying When Miasma Demon enters, you may discard any number of cards
Permanents leaving the battlefield is such an easy trigger to build around
She is incredibly strong, super hard to remove, and can build you a board out of nowhere
On the other hand, legends in the main set can be designs built around the character independently of other cards to spark new archetypes of decks
These lands represent some of the best dual lands in MTG specifically for Commander pods, where their reliability justifies their inclusion over faster alternatives that falter in multiplayer settings