Madman's Knowledge

{t}: Add {b}
{t}, Pay 2 life: Draw a card.
{t}, Pay 4 life, Exile Madman's Knowledge:
You may play a non-artifact spell you own from
exile for {2} in addition to its mana cost.
Making contact with eldritch wisdom is a blessing,
for even if it drives one mad, it allows one to serve a grander purpose, for posterity.