Vex Deterrent

With Evokers now having a chance to come as part of Pillager raids, I think we need some kind of Vex Repellent.  A suitably secured village can be proof against most raids, with a wall keeping them out.  But their vexes can go quite some ways out to chase down and kill helpless Villagers.

I suggest that there is a mob or block or device that will keep them at bay.  With the vaguely angel/devil theme they have going on, perhaps they will avoid Clerics, or some kind of "holy symbol."

Or perhaps they can't go through iron, be it iron blocks, bars, ores, by virtue of their iron sword giving them some connection to that metal.