Artisan of Forms

When Artisan of Forms becomes a copy of a creature, it's neither entering nor leaving the battlefield. Any enters-the-battlefield or leaves-the-battlefield abilities won't trigger.

If another creature becomes a copy of Artisan of Forms, it will become a copy of whatever Artisan of Forms is currently copying (if anything), plus it will have the triggered ability.

The copy effect lasts indefinitely. Often, it will last until it is overwritten by another copy effect (if it copies another creature on a future turn, perhaps).