Lurking Jackals — ruling 1

A noncreature permanent that turns into a creature can attack, and its {T} abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.

Lurking Jackals — ruling 2

Once it becomes a creature, it will not change back into an enchantment if your opponent's life total goes back above 10.

Lurking Jackals — ruling 3

Once it becomes a creature, it is no longer an enchantment.

Lurking Jackals : règles, fonctionnement et interactions (MTG)

Lurking Jackals 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

When an opponent has 10 or less life, if this permanent is an enchantment, it becomes a 3/2 Jackal creature.

How it works : Lurking Jackals

Original English text — Wizards of the Coast / Scryfall

#1August 1, 2008· Wizards of the Coast
A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.
No other card is named in this ruling.
#2October 4, 2004· Wizards of the Coast
Once it becomes a creature, it will not change back into an enchantment if your opponent's life total goes back above 10.
No other card is named in this ruling.
#3October 4, 2004· Wizards of the Coast
Once it becomes a creature, it is no longer an enchantment.
No other card is named in this ruling.