Cheapest priced copy (Commander 2020): $0.59 at Card Kingdom, near mint, their price list as of .
Archon of Valor's Reach 
Creature — Archon · 5/6 · Rare · Commander 2020 · #202
Flying, vigilance, trample
As this creature enters, choose artifact, enchantment, instant, sorcery, or planeswalker.
Players can't cast spells of the chosen type.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.59 to $12.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Battlebond | 74 | Rare | $0.99 | $12.99 |
| Commander 2020 | 202 | Rare | $0.59 | — |
2 rulings from Wizards of the Coast
- 8 June 2018Whether it’s legal to cast a spell is determined before its costs are paid. This means that if Archon of Valor’s Reach has sorcery as the chosen type, you can’t cast Morbid Curiosity, even if you wish to sacrifice Archon of Valor’s Reach to do so.
- 8 June 2018The enters-the-battlefield effect of Archon of Valor’s Reach is a replacement effect that doesn’t use the stack. No player can cast spells or activate abilities after it has entered the battlefield but before you choose a card type.