Kari Zev's Expertise

Kari Zev's Expertise can target any creature or Vehicle, even one that you already control or that is already untapped.

If you cast a card "without paying its mana cost," you can't choose to cast it for any alternative costs, such as emerge costs. You can, however, pay additional costs. If the card has any mandatory additional costs, such as that of Cathartic Reunion, you must pay those to cast the card.

Any triggered abilities that trigger while performing the Expertise spell's first effect won't be put onto the stack until after you're done casting your free spell. They're put onto the stack at the same time as any abilities that triggered while casting that spell regardless of the order in which those abilities triggered.

A card's mana value is determined solely by the mana symbols printed in its upper right corner. The mana value is the total amount of mana in that cost, regardless of color. For example, a card with mana cost {1}{U}{U} has mana value 3. Ignore any alternative costs, additional costs, cost increases, or cost reductions that could apply to it. A card with no mana cost has a mana value of 0.

If the card has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.