Sigil of the New Dawn
Enchantment
Whenever a creature is put into your graveyard from the battlefield, you may pay 
. If you do, return that card to your hand.
"We lay our dead to rest in a beautiful bed, in hopes that the Ancestor will think it a fit cradle for the next life." —Mystic elder
Tony Szczudlo
Onslaught (ONS)
• #55Rulings
Sigil of the New Dawn's ability triggers if a creature you own dies under another player's control.
(wotc • 2018-12-07)
If a creature you own dies at the same time that Sigil of the New Dawn leaves the battlefield, Sigil of the New Dawn's ability triggers for that creature.
(wotc • 2018-12-07)
Rulings
Sigil of the New Dawn's ability triggers if a creature you own dies under another player's control.
(wotc • 2018-12-07)
If a creature you own dies at the same time that Sigil of the New Dawn leaves the battlefield, Sigil of the New Dawn's ability triggers for that creature.
(wotc • 2018-12-07)