Cheapest priced copy (The List): $0.69 at Card Kingdom, near mint, their price list as of .
Ironscale Hydra 
Creature — Hydra · 5/5 · Rare · The List · #THB-296
If a creature would deal combat damage to this creature, prevent that damage and put a +1/+1 counter on this creature.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.69 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The List | THB-296 | Rare | $0.69 | — |
| Theros Beyond Death | 296 | Rare | $0.69 | $3.49 |
2 rulings from Wizards of the Coast
- 24 January 2020If damage that can’t be prevented is dealt to Ironscale Hydra, the damage is dealt and you’ll simultaneously put a +1/+1 counter on it, before the game checks for lethal damage.
- 24 January 2020You put only one +1/+1 counter on Ironscale Hydra per creature whose combat damage is prevented, no matter how much damage would have been dealt.