Vastwood Hydra — ruling 1

The ability that triggers when Vastwood Hydra dies doesn’t target any of the creatures. You can choose to put counters on a creature with protection from green, for example.

Vastwood Hydra — ruling 2

You choose how the counters will be distributed when the ability resolves.

Vastwood Hydra — ruling 3

In some unusual cases, Vastwood Hydra will have enough -1/-1 counters put on it to make its toughness 0 or less. If this happens, the ability will still distribute a number of +1/+1 counters equal to the number of +1/+1 counters on Vastwood Hydra before the -1/-1 counters were put on it. For example, if Vastwood Hydra has two +1/+1 counters on it and three -1/-1 counters are put on it, two +1/+1 counters will be distributed.

Vastwood Hydra : règles, fonctionnement et interactions (MTG)

Vastwood Hydra is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

This creature enters with X +1/+1 counters on it. When this creature dies, you may distribute a number of +1/+1 counters equal to the number of +1/+1 counters on this creature among any number of creatures you control.

How it works : Vastwood Hydra

Original English text — Wizards of the Coast / Scryfall

#1July 1, 2013· Wizards of the Coast
The ability that triggers when Vastwood Hydra dies doesn’t target any of the creatures. You can choose to put counters on a creature with protection from green, for example.
No other card is named in this ruling.
#2July 1, 2013· Wizards of the Coast
You choose how the counters will be distributed when the ability resolves.
No other card is named in this ruling.
#3July 1, 2013· Wizards of the Coast
In some unusual cases, Vastwood Hydra will have enough -1/-1 counters put on it to make its toughness 0 or less. If this happens, the ability will still distribute a number of +1/+1 counters equal to the number of +1/+1 counters on Vastwood Hydra before the -1/-1 counters were put on it. For example, if Vastwood Hydra has two +1/+1 counters on it and three -1/-1 counters are put on it, two +1/+1 counters will be distributed.
No other card is named in this ruling.