They will not be able to issue you any advice about the game state or what decisions you should make
But generally this is a rare occurrence, and most players use the term in good faith, just to encourage faster play in tournament situations
Additionally, when paired with instants, Hullbreaker Horror can be used to repeatedly return spells opponents try to cast back to their hands, preventing opponents from making any progress in a game
This is played loads more since when it swings, the controller loses two life and you gain it, so it's a win-con
GameStop Pro Benefits Level up to Pro
That said, Id still encourage trying the format out with proxies or free Magic programs if youre interested