The player gets the option to pay when this triggered ability resolves
10 Cut In Red mana is usually tied with black mana for the best removal in any expansion set, including cards like Cut In
Within Jund graveyard-focused decks, this card is going to be a literal monster
This white instant works best in decks with lots of powerful enters abilities to retrigger, which gives it utility when you dont have to protect your creatures
Beast Within is a fantastically versatile card with great balancing that sees play all over the place, any deck with a weakness to certain permanent types or any deck that really doesn't care about 3/3 tokens generally ends up playing it
One thing Ive discovered playing Quandrix is that your late game is very powerful, with cards like Bookwurm and spells that make large fractal tokens, so its important to protect yourself from getting run over early