Magic the Gathering: Revised (Base Set)173-A

*Name: Rock Hydra
Type: Summon Hydra
Play Cost: X Colorless, 2 Mountains
Stats: 0 Power/0 Toughness
Game Text: Put X +1/+1 counters (heads) on Hydra. Each point of damage Hydra suffers kills one head unless controller spends M per head. During controller's upkeep, new heads may be grown for MMM apiece.
*Source: Front of card

*Name: Rock Hydra
Type: Creature — Hydra
Play Cost: X Colorless, 2 Mountains
Stats: 0 Power/0 Toughness
Game Text: Rock Hydra enters the battlefield with X +1/+1 counters on it.
For each 1 damage that would be dealt to Rock Hydra, if it has a +1/+1 counter on it, remove a +1/+1 counter from it and prevent that 1 damage.
M: Prevent the next 1 damage that would be dealt to Rock Hydra this turn.
MMM: Put a +1/+1 counter on Rock Hydra. Activate this ability only during your upkeep.
*Source: gatherer.wizards.com