Atraxa's Skitterfang — ruling 1

You don't choose a target for Atraxa's Skitterfang's last ability at the time it triggers. Rather, a second "reflexive" ability triggers when you remove an oil counter this way. You choose a target for that ability as it goes on the stack. Each player may respond to this triggered ability as normal.

Atraxa's Skitterfang — ruling 2

You choose which ability the target creature gets as the reflexive ability resolves. Players may not wait to see what ability you choose before deciding whether to respond to it.

Atraxa's Skitterfang : règles, fonctionnement et interactions (MTG)

Atraxa's Skitterfang 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 three oil counters on it. At the beginning of combat on your turn, you may remove an oil counter from this creature. When you do, target creature you control gains your choice of flying, vigilance, deathtouch, or lifelink until end of turn.

How it works : Atraxa's Skitterfang

Original English text — Wizards of the Coast / Scryfall

#1February 4, 2023· Wizards of the Coast
You don't choose a target for Atraxa's Skitterfang's last ability at the time it triggers. Rather, a second "reflexive" ability triggers when you remove an oil counter this way. You choose a target for that ability as it goes on the stack. Each player may respond to this triggered ability as normal.
No other card is named in this ruling.
#2February 4, 2023· Wizards of the Coast
You choose which ability the target creature gets as the reflexive ability resolves. Players may not wait to see what ability you choose before deciding whether to respond to it.
No other card is named in this ruling.