2009-05-01 : If Arsenal Thresher and another artifact are entering the battlefield from your hand at the same time, you may reveal that other artifact for Arsenal Thresher. If that artifact is a second Arsenal Thresher, you may reveal each Arsenal Thresher for the other.

2009-05-01 : If multiple Arsenal Threshers are entering the battlefield at the same time (for example, if Warp World is resolving), you may reveal the same artifact cards from your hand for each of them.