I could imagine a situation in which someone tries to Epic Downfall our Erebos and we actually choose to sacrifice our Ayara to his -2/-1 ability in order to drop our devotion back down below five, making Epic Downfall countered upon resolution
A mana base can be simple (say, seventeen Plains in an all-white, 40-card deck) or it can be quite complex: featuring multiple colors of mana, lands with unusual abilities, and indirect methods of making mana (via artifacts, creatures, or spells)
This already existed as the heavily played four mana to drop and four to use and colorless Quicksilver Amulet
They also work decently with cards that care about a certain amount of something in the graveyard
BPhillipYork: It really seems like the Steward of Fate should be like, a card selection card, maybe Brainstorm
This, in turn, has led to the rise of a new deck built, Panderburst, which has been putting up strong results