Casting cost change to black

[Noblellama]

Is there a spell or ability anywhere that changes casting costs to black?

[Rass]

Closest thing I can think of  {Initiates of the Ebon Hand}

[Rasser]

Probably doesn't help but
{Urborg, Tomb of Yawgmoth}

[Rasser]

You could use  {Gilded Lotus}.
Or would that be to slow?

[Birdbrain]

There's a card in innistrad that lowers casting cost...umm...

[Birdbrain]

{heartless summoning}