The permanents have an "attack order", like the creatures, so the Langolier would attack the 1. If not existent, the 2.. etc etc.
It's a great idea but I believe it's way OP, since an early Langolier would eat all pillars played, making the use of Enchant Artifact more common.. and less mono decks.. and more rainbows.. or mono earth.. etc etc..
BUT DAMN, ADD TO THE GAME AND LET'S SEE WHAT HAPPENS! 8)