Remove the "Creates Frost Walls and Flees" mod.

While I agree it's pretty funny seeing the monster move so fast the first time, the mod quickly becomes extremely annoying when you actually need to kill said monster.
There was a Crucible encounter where I thought I had killed every monster, but the experience didn't pop, so I started wondering what the hell was going on, only to find a single rare monster that had fled to the other side of the entire map.
And another time I had a Harvest encounter with a monster that also had the "Ambushes" mod that made it disappear into a smoke cloud as soon as it was done running away, making killing it a huge hassle.

I feel the mod's only purpose is to piss people off rather than adding something to the experience. It seems like pointless trolling.

Oh, ghod, yes! =@[.]@=

Seconding this.
Just wasted a 2k trip in the mines because I found a red beast with that mod in it, and it just bolted into the caverns. Every time i find it it casts it again and flees to depth 15000000 again. Not fun, not engaging, not useful in any measure to the gameplay.