Rather than consort with demons, the Quietus Cult seeks wisdom from the dead.

Soulcipher Board // Cipherbound Spirit

Flying
Cipherbound Spirit can block only creatures with flying.
{3}{U}: Draw two cards, then discard a card.

Soulcipher Board enters with three omen counters on it.
{1}{U}, {T}: Look at the top two cards of your library. Put one of them into your graveyard.
Whenever a creature card is put into your graveyard from anywhere, remove an omen counter from Soulcipher Board. Then if it has no omen counters on it, transform it.

Innistrad: Double Feature

Innistrad: Crimson Vow

Soulcipher Board's last ability triggers when a creature card is put into a graveyard from anywhere. This is different than an ability that triggers when a creature dies. Notably, a noncreature card on the battlefield that becomes a creature and dies (such as an animated land) won't cause this ability to trigger. Similarly, a creature card on the battlefield that has been made a noncreature permanent (such as one enchanted with Minimus Containment) will cause this ability to trigger when that card is put into your graveyard.

Token creatures dying never cause Soulcipher Board's last ability to trigger.