Banneret and Evoke

[DeepfriedDynamite]

If i have a brighthearth banneret and i evoke a shriekmaw, does it cost B to play or 1B?

[Sanguine Voyeur]

It will cost only black. Evoke is an alternative way to play something and it's cost can be lowered/raised as a spell can.

[Tosh]

Sanguine Voyeur is right.
They also work with prowl (just to head off any further questions).