The Drunken Lizard Pub

One run-through is good enough for me.

Then I added more around the outside, and retreated behind one more that will finish him off if the first blast doesn't kill him.

Then I just moved the barrels closer, and filled in around him.

What I did almost killed him with one shot. I lured him to his second right turn out of his starting area.

Then I made walls I could run through, but he doesn't approach. This requires giving him a swipe at you, but you can heal all you want once you get him trapped.