If another player controls Arbalest Elite during your next untap step, the part of the effect that keeps it from untapping does nothing. It won't try to apply during a future untap step.
22-09-2011
wotc
If the creature is an illegal target when Arbalest Elite's ability tries to resolve, the ability won't resolve and none of its effects will happen. Arbalest Elite will untap during its controller's next untap step.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.