When the battle phase starts, choose a unit in any arena or your opponent's build zone. Remove the card from its sleeve, if any, and drop Homing Missile from at least 30 centimeters above the playing area. If Homing Missile lands naturally so that it touches or overlaps the chosen unit, it does 3 damage to that unit.
The IDC has ruled for online gameplay only that Homing Missile simply does 3 damage to the unit selected at the start of the battle phase, so the text in the plugin has an erratum.