Cheapest priced copy (Ikoria: Lair of Behemoths): $0.35 at Card Kingdom, near mint, their price list as of .
Essence Symbiote 
Creature — Beast · 2/2 · Common · Ikoria: Lair of Behemoths · #149
Whenever a creature you control mutates, put a +1/+1 counter on that creature and you gain 2 life.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ikoria: Lair of Behemoths | 149 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 17 April 2020If Essence Symbiote mutates, its ability triggers.
- 17 April 2020You gain 2 life when Essence Symbiote’s ability resolves, even if you can’t put a +1/+1 counter on the mutated creature (most likely because it’s left the battlefield).