The more I think about this new colorless mana
symbol, the more I like it. Notice, for example,
how it operates in the context of Dread Defiler
to compel an actual new style of deckbuilding.
Yes, you heard me - activating its ability
consistently requires colorless mana in addition
to generic mana, meaning that any deck that uses
it must include both cards that tap for black
mana and cards that tap for colorless mana. The
basic math may be much the same as we're
familiar with for manabases, but the goal is
novel and it's going to lead to interesting
choices: will we see Unknown Shores in
mono-colored decks, and Pristine Talisman in
unusual places? If this card is your proposed
payoff for making those choices, you could do
much worse: any deck that can hit seven mana is
probably going to include some comparably large
creatures to the Defiler itself, meaning that if
it survives, you will be able to close the game
out in a way that few decks will be equipped to
stop.