Sage of Mysteries
Creature — Human Wizard
Constellation — Whenever an enchantment you control enters, target player mills two cards.
"I see destruction, suffering, and one tormented glimmer of hope."
John Stanko
Rulings
An Aura spell that has an illegal target when it tries to resolve doesn’t resolve and is instead put into its owner’s graveyard. It doesn’t enter the battlefield, so constellation abilities don’t trigger.
(wotc • 2020-01-24)
A constellation ability triggers whenever an enchantment enters the battlefield under your control for any reason. Enchantments with other card types, such as enchantment creatures, will also cause constellation abilities to trigger.
(wotc • 2020-01-24)
Rulings
An Aura spell that has an illegal target when it tries to resolve doesn’t resolve and is instead put into its owner’s graveyard. It doesn’t enter the battlefield, so constellation abilities don’t trigger.
(wotc • 2020-01-24)
A constellation ability triggers whenever an enchantment enters the battlefield under your control for any reason. Enchantments with other card types, such as enchantment creatures, will also cause constellation abilities to trigger.
(wotc • 2020-01-24)