What do you do in "Black Forest choke point" situations? (Picture inside)

http://ift.tt/2BzZctl

So whenever I play black forest maps, I always end up in a situation where neither of us can push through the choke point because the other player's onargars will destroy our armies. Both armies are barely out of reach of each other's trebs, and it's super risky to try to move yours forward. Idk what to do here and somehow I end up getting pushed anyway.

Thanks!