While the counter on its own is a one time thing, having this trigger at the beginning of combat and then the ability to get that creature back with haste for that same combat makes a very tight window for opponents to deal with your shenanigans
For example, as the monored Karlach, Fury of Avernus has Choose a Background, you can partner it up with any Background, like Master Chef
Uniquely, Mox Ambers position is also dependent on the current card pool
An indestructible 6/7 enchantment creature that costs three generic, one green, and one white, she rewards casting creature spells with letting you tutor for a forest or plains land
But if you have a way to control whats in your graveyard at all, you can make it wildly overpowered
To help you find these powerful supporters, many Charizard ex players run Tatsugiri from Twilight Masquerade to enable more consistency