How to beat Gut Trasher on hard ?

I tried 2 wars, 1 DW rage, and 2 theatrics. All strongest guys possible, 85% + win rate. I was able to remove max 1/3 of his HP he just decimate everyone. I was thinking about some counteratack heroes.

I am lvl 20 now, isnt it too soon to try run gauntlet on hard at this LVL ?