Cheapest priced copy (Wilds of Eldraine Commander): $5.99 at Card Kingdom, near mint, their price list as of .
Setessan Champion 
Creature — Human Warrior · 1/3 · Rare · Theros Beyond Death Promos · #198p
Constellation — Whenever an enchantment you control enters, put a +1/+1 counter on this creature and draw a card.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
6 printings · $5.99 to $32.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 912 | Rare | $6.49 | — |
| Theros Beyond Death Promos | 198p | Rare | $6.49 | $9.99 |
| Theros Beyond Death Promos | 198s | Rare | — | $9.99 |
| Theros Beyond Death | 198 | Rare | $6.49 | $7.99 |
| Theros Beyond Death | 331 | Rare | $9.49 | $32.99 |
| Wilds of Eldraine Commander | 132 | Rare | $5.99 | — |
3 rulings from Wizards of the Coast
- 24 January 2020An 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.
- 24 January 2020A 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.
- 24 January 2020If 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.