Sip of Hemlock — ruling 1

If the creature is an illegal target when Sip of Hemlock tries to resolve, it won't resolve and none of its effects will occur. The creature's controller won't lose 2 life. However, if Sip of Hemlock resolves and the creature isn't destroyed (perhaps because it regenerated or had indestructible), the creature's controller will still lose 2 life.

Sip of Hemlock : règles, fonctionnement et interactions (MTG)

Sip of Hemlock 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

Destroy target creature. Its controller loses 2 life.

How it works : Sip of Hemlock

Original English text — Wizards of the Coast / Scryfall

#1September 15, 2013· Wizards of the Coast
If the creature is an illegal target when Sip of Hemlock tries to resolve, it won't resolve and none of its effects will occur. The creature's controller won't lose 2 life. However, if Sip of Hemlock resolves and the creature isn't destroyed (perhaps because it regenerated or had indestructible), the creature's controller will still lose 2 life.
No other card is named in this ruling.