Cow-tapult is a reference to a scene early in the film, in which French soldiers occupying a castle use a catapult to fling a cow (the flavor text is French for Fetch the cow!) and other barnyard animals at King Arthur and his knights
As soon as the equipped creature inflicts combat damage, one of the newly built mechanics of the Forgotten Realms-Edition triggers, the dice roll
It's made up of a cohesive theme that builds upon itself by first creating artifact creatures and then using effects like Urzas to further expand your board, culminating in fun and threatening gameplay
The Adventure sides of the red and blue ones are all cheap mana values with decent effects attached, and I would definitely consider them for this deck
And people have to sign off on things at every step along the way
The cards are simply referred to as promo cards, but are also known as black star promo cards