Cheapest priced copy (Tarkir: Dragonstorm): $2.29 at Card Kingdom, near mint, their price list as of .
Warden of the Grove 
Creature — Hydra · 2/2 · Rare · Tarkir: Dragonstorm · #166
At the beginning of your end step, put a +1/+1 counter on this creature.
Whenever another nontoken creature you control enters, it endures X, where X is the number of counters on this creature. (Put X +1/+1 counters on the creature that entered or create an X/X white Spirit creature token.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
4 printings · $2.29 to $6.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tarkir: Dragonstorm Promos | 166p | Rare | $2.49 | $2.99 |
| Tarkir: Dragonstorm Promos | 166s | Rare | — | $4.49 |
| Tarkir: Dragonstorm | 166 | Rare | $2.29 | $2.49 |
| Tarkir: Dragonstorm | 351 | Rare | $2.79 | $6.99 |
4 rulings from Wizards of the Coast
- 4 April 2025You choose whether to put +1/+1 counters on the creature or create a Spirit token as the ability that includes the endure instruction is resolving. No player may take actions between the time you choose and the time that counters are added or tokens are created.
- 4 April 2025The value of X is determined as the last ability resolves. If Warden of the Grove is no longer on the battlefield at that time, the number of counters on it as it last existed on the battlefield is used to determine how many +1/+1 counters to put on the creature that endured or the power and toughness of the Spirit token created.
- 4 April 2025If you can’t put +1/+1 counters on the creature for any reason as an endure ability resolves (for example, if the creature is no longer on the battlefield), you’ll just create a Spirit token.
- 4 April 2025If a noncreature permanent is instructed to endure, the effect is the same. You can put +1/+1 counters on that permanent or create a Spirit token.