Boneshatter League starter

As per topic, how's boneshatter single-target and map clear? I've never tried it, and I will test it in Standard. How much investment is needed for the build to be able to do Uber bosses? 1 mirror?

I got some of the leftover gears from Mirage and leveled up Boneshatter to 21/20 and some of the necessary gems. Got some average 2H axe and 4k++ armour.

Boneshatter - Brutality - Impale - Ruthless - Melee Physical Damage - Close Combat.

Any advice and help is greatly appreciated. Thanks.