[Mivereous]

Sorry to tell ya, but they didn't. Just led a Wings of Fire around a bush for about 50 rounds, around a rock for 30 rounds, and laughed as I confirmed that yes, Barghest and Corruptor have Flier tag (tested with Skyshot), but still don't move through walls or the jail bars in the Castles for 30-50 rounds on each of those. Reynes eventually got bored and blasted them down for me. Corruptors also did not move through boulders or bushes; unable to procure a Barghest in a testable environment. Also, all the Flier tagged monsters are moving around their allies, rather than through them.