Nivmagus Elemental — ruling 1

You exile an instant or sorcery spell you control from the stack, not an instant or sorcery card in any other zone.

Nivmagus Elemental — ruling 2

Exiling a spell is not the same as countering it, although the spell won’t resolve in both cases. You may exile a spell that can’t be countered.

Nivmagus Elemental — ruling 3

You can exile a copy of an instant or sorcery spell to activate Nivmagus Elemental’s ability if you control the copy.

Nivmagus Elemental : règles, fonctionnement et interactions (MTG)

Nivmagus Elemental 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

Exile an instant or sorcery spell you control: Put two +1/+1 counters on this creature. (That spell won't resolve.)

How it works : Nivmagus Elemental

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2012· Wizards of the Coast
You exile an instant or sorcery spell you control from the stack, not an instant or sorcery card in any other zone.
No other card is named in this ruling.
#2October 1, 2012· Wizards of the Coast
Exiling a spell is not the same as countering it, although the spell won’t resolve in both cases. You may exile a spell that can’t be countered.
No other card is named in this ruling.
#3October 1, 2012· Wizards of the Coast
You can exile a copy of an instant or sorcery spell to activate Nivmagus Elemental’s ability if you control the copy.
No other card is named in this ruling.