Cheapest priced copy (Double Masters 2022): $0.79 at Card Kingdom, near mint, their price list as of .
Conclave Mentor 
Creature — Centaur Cleric · 2/2 · Uncommon · March of the Machine Commander · #320
If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on that creature instead.
When this creature dies, you gain life equal to its power.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.79 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters 2022 | 195 | Uncommon | $0.79 | $0.99 |
| Core Set 2021 | 216 | Uncommon | $0.79 | $1.49 |
| March of the Machine Commander | 320 | Uncommon | $0.99 | — |
| The List | M21-216 | Uncommon | $0.99 | — |
5 rulings from Wizards of the Coast
- 23 June 2020If a creature you control would enter the battlefield with a number of +1/+1 counters on it, it enters with that many plus one instead.
- 23 June 2020Conclave Mentor's first ability doesn't apply to itself if it's somehow entering the battlefield with a +1/+1 counter on it.
- 23 June 2020If two or more effects attempt to modify how many counters would be put onto a creature you control, you choose the order to apply those effects, no matter who controls the sources of those effects.
- 23 June 2020Use Conclave Mentor's power as it last existed on the battlefield to determine how much life you gain.
- 23 June 2020If you control two Conclave Mentors, the number of +1/+1 counters put on a creature is two plus the original number. Three Conclave Mentors add three, and so on.