Mordekaisers Metal swarm chooses its own swarm. [GAMEPLAY]

Was playing an ARAM with friends and i had what i thought was fortune to get Lord Morde! Unfortunately my W, Metal Swarm, wouldnt apply to the champion of my choosing and only to the closest champion. I understand that the swarm will priorotize champs over minions (even though sometimes i wish it would for some health gainin purposes) but prioritizing champs closer to me than my intended target? No bueno. Not sure if this is happening on the rift but in the abyss its a problem.