In most cases, these come in the form of spells that can counter a very popular deck being used by a lot of players in the competitive ladder so that you wont get automatically destroyed by those decks
It's been a solid deck in the past but has fallen out of the meta with the rise of new archetypes
Basically, you sacrifice the artifact, activate your merfolk commander to play it from your graveyard, trigger Mirran Spy to untap your commander, then rinse and repeat as many times as cards you have left in your deck
This is especially important with Secret Lair, Universes Beyond, and premium variants
While she is out, nothing can be removed through damage or destroying effects
Although the United States didn't receive their cards as early as some other countries, it is encouraging to see that it has made its way here for USA players of Disney Lorcana