Rulings

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.