Lowland Basilisk — ruling 1

If a creature leaves the battlefield before the end of combat, then the Lowland Basilisk effect on it will end.

Lowland Basilisk — ruling 2

If it damages a creature outside of combat, its effect will destroy the creature at the end of the next combat.

Lowland Basilisk : règles, fonctionnement et interactions (MTG)

Lowland Basilisk 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 deals damage to a creature, destroy that creature at end of combat.

How it works : Lowland Basilisk

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
If a creature leaves the battlefield before the end of combat, then the Lowland Basilisk effect on it will end.
No other card is named in this ruling.
#2October 4, 2004· Wizards of the Coast
If it damages a creature outside of combat, its effect will destroy the creature at the end of the next combat.
No other card is named in this ruling.