Nimana Sell-Sword — ruling 1

This ability triggers on this creature entering, so it will enter with its unmodified power and toughness, and then receive a +1/+1 counter a short time later. It does not enter with the +1/+1 counter already on it.

Nimana Sell-Sword : règles, fonctionnement et interactions (MTG)

Nimana Sell-Sword 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

Whenever this creature or another Ally you control enters, you may put a +1/+1 counter on this creature.

How it works : Nimana Sell-Sword

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2009· Wizards of the Coast
This ability triggers on this creature entering, so it will enter with its unmodified power and toughness, and then receive a +1/+1 counter a short time later. It does not enter with the +1/+1 counter already on it.
No other card is named in this ruling.