Phyrexian Altar

Sacrifice a creature: Add one mana of any color.
"I've done a lot. Gods know I've tried. But it was all
in vain. Ashnod became a victim to Endrek Sahr's machinations. All is lost. We shouldn not have played
with knowledge far greater than we could handle. She
is now in my head and I'll soon join the others.
Forgive us for what we have done.
-Last diary entry"