Sentence of Doom — Ruling

Effetto 0

You can activate a face-down Sentence of Doom at any time except the Damage Step.

This card's effect that adds Fiend monsters from your Graveyard or that are banished to your hand starts a Chain. (It cannot be activated during the Damage Step. You can activate this Set card and this effect as part of the same Chain Link.)
This effect targets your Fiend monsters that are banished and/or in your Graveyard. (You can target 1 or more monsters, up to the number of Destiny Board and/or "Spirit Message" cards that are face-up on your field.)

This card's effect that places a "Spirit Message" card face-up in your Spell & Trap Zone starts a Chain. (It does not target, and cannot be activated during the Damage Step.)
Sending this card that is already face-up in your Spell & Trap Zone to the Graveyard is the cost to activate this effect.