Cheapest priced copy (Guilds of Ravnica): $0.49 at Card Kingdom, near mint, their price list as of .
Deafening Clarion 
Sorcery · Rare · Guilds of Ravnica Promos · #165p
Choose one or both —
• Deafening Clarion deals 3 damage to each creature.
• Creatures you control gain lifelink until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.49 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Guilds of Ravnica | 165 | Rare | $0.49 | $0.49 |
| Guilds of Ravnica Promos | 165p | Rare | $0.49 | $1.99 |
| Guilds of Ravnica Promos | 165s | Rare | — | $0.99 |
2 rulings from Wizards of the Coast
- 5 October 2018Deafening Clarion’s second mode affects only creatures you control at the time it resolves. Creatures you begin to control later in the turn won’t gain lifelink.
- 5 October 2018A creature you control that’s dealt lethal damage by Deafening Clarion’s first mode will still be on the battlefield to gain lifelink from the spell’s second mode before that creature dies.