When you activate this card, you choose which "●" to activate. (This card cannot be activated during the Damage Step.)[1]
Applying the selected "●" effect and Setting this card in its Spell & Trap Zone do not happen simultaneously.[1]
The effect that sends a monster from your hand or face-up from your field to the Graveyard and adds a Flip monster from your Deck to your hand does not target. (Sending the monster to the Graveyard and adding the Flip monster from your Deck to your hand happen simultaneously.)[1]
The effect that sends a Flip monster from your hand or face-up from your field to the Graveyard and adds a monster from your Deck to your hand does not target. (Sending the Flip monster to the Graveyard and adding the monster from your Deck to your hand happen simultaneously.)[1]
Q&A Rulings
Q: "Advanced Dark" is face-up in the Field Zone, and its effect that treats "Crystal Beast" monsters on the field and in the Graveyard as DARK is applying. In this situation, if I activate "Subterror Succession" and send a "Crystal Beast" monster to the Graveyard, what happens?
A: While the effect of "Advanced Dark" is applying, if you send Crystal Beast Topaz Tiger from your hand to the Graveyard with the effect of "Subterror Succession", you must add an EARTH Flip Monster from your Deck to your hand. Also, while the effect of "Advanced Dark" is applying, if you send a face-up "Crystal Beast Sapphire Pegasus" from your Monster Zone to the Graveyard with the effect of "Subterror Succession", you must add a DARK Flip Monster from your Deck to your hand.[2]
Q: When applying the first effect of "Subterror Succession", can I choose a Token monster in my Monster Zone as the monster to send to the Graveyard?
A: When sending a monster to the Graveyard with the effect of "Subterror Succession", you can choose a Token monster. In that case, since the Token disappears instead of being sent to the Graveyard, you cannot add a Flip monster from your Deck to your hand.[3]
Q: When applying the first effect of "Subterror Succession", can I choose "Shaddoll Core" treated as a monster by its own effect as the monster to send to the Graveyard?
A: When sending a monster to the Graveyard with the effect of "Subterror Succession", you can choose a "Shaddoll Core" treated as a monster. Since "Shaddoll Core" is treated as a DARK monster, you add a DARK Flip monster from your Deck to your hand.[4]
A: When sending a Flip monster to the Graveyard with the effect of "Subterror Succession", you can choose "Performapal Momoncarpet", which is a Pendulum Monster as well as a Flip monster. In that case, since "Performapal Momoncarpet" is added face-up to the Extra Deck instead of sent to the Graveyard, you cannot add a monster from your Deck to your hand.[5]