Can you choose to put all your damage on one of two units and deliberately not kill the second (to force a specific response like Zhonya's)?

Ruling: You cannot overkill a unit if there are still more units to assign damage to. Once you have distributed enough damage for lethal on one unit, you must move on to the next unit.

Nuances:

• You can only over-assign damage to the last unit in the damage assignment order
• This ruling was confirmed via red text and is consistently applied by judges