Noxious Hatchling — ruling 1

If you cast a spell that’s both of the listed colors, both abilities will trigger. You’ll remove a total of two -1/-1 counters from the Hatchling.

Noxious Hatchling — ruling 2

If there are no -1/-1 counters on it when the triggered ability resolves, the ability does nothing. There is no penalty for not being able to remove a counter.

Noxious Hatchling : règles, fonctionnement et interactions (MTG)

Noxious Hatchling 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 four -1/-1 counters on it. Wither (This deals damage to creatures in the form of -1/-1 counters.) Whenever you cast a black spell, remove a -1/-1 counter from this creature. Whenever you cast a green spell, remove a -1/-1 counter from this creature.

How it works : Noxious Hatchling

Original English text — Wizards of the Coast / Scryfall

#1August 1, 2008· Wizards of the Coast
If you cast a spell that’s both of the listed colors, both abilities will trigger. You’ll remove a total of two -1/-1 counters from the Hatchling.
No other card is named in this ruling.
#2August 1, 2008· Wizards of the Coast
If there are no -1/-1 counters on it when the triggered ability resolves, the ability does nothing. There is no penalty for not being able to remove a counter.
No other card is named in this ruling.