2021-11-19 : 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.

2021-11-19 : Token creatures dying never cause Soulcipher Board's last ability to trigger.