Boneyard Scourge
Creature — Zombie Dragon
Flying
Whenever a Dragon you control dies while this card is in your graveyard, you may pay 
. If you do, return this card from your graveyard to the battlefield.
Death arrives on tattered wings and stolen bones.
Grzegorz Rutkowski
Commander 2017 (C17)
• #15Rulings
If Boneyard Scourge leaves your graveyard before its triggered ability resolves, it won't be returned to the battlefield.
(wotc • 2017-08-25)
If Boneyard Scourge dies at the same time as another Dragon you control, its ability won't trigger.
(wotc • 2017-08-25)
Rulings
If Boneyard Scourge leaves your graveyard before its triggered ability resolves, it won't be returned to the battlefield.
(wotc • 2017-08-25)
If Boneyard Scourge dies at the same time as another Dragon you control, its ability won't trigger.
(wotc • 2017-08-25)