Setessan Champion

Constellation — Whenever an enchantment you control enters, put a +1/+1 counter on this creature and draw a card.

"A blessing is not a gift. It is a duty."

Wilds of Eldraine Commander

Constellation — Whenever an enchantment enters the battlefield under your control, put a +1/+1 counter on Setessan Champion and draw a card.

Commander Masters

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Theros Beyond Death

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.

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.

If Setessan Champion leaves the battlefield after its ability has triggered, you still draw a card even though you won't put a +1/+1 counter on Setessan Champion.