Just recently, I was talking about Tidehollow
Sculler as a great reason to go black in a Soul
Sisters deck. I think Ayli might be an even
better reason. Her abilities are certainly more
on-theme, and Soul Sisters tends to play a lot
of cheap creatures and/or token generators that
can fuel both her abilities. Honestly, she's
even pretty good in archetypes that don't care
as explicitly about their life total - there are
far worse ways to trigger Grave Pact at will -
and you can never have too many ways to
invalidate answers like Vedalken Shackles and
Corrupted Conscience.