Have a Nice Death

This is a random encounter that replaces Brad, the first Sorrow boss at the end of the first set of levels.

He is similar to Brad but has faster attacks and has eye lasers instead of a few of Brad's attacks.

I died my first attempt and the next attempt was also Barnaby.

I think I was about 15-20 attempts into this game when I ran into him.

oX xM1K3x Xo: added
I'd just like to add to this solution.
After 44 hours and countless runs not getting the Barnaby boss fight I found out that you must first purchase the 'Boulderain' spell from the shop.
Only then will he become available. I got him 2nd run after buying this spell from the shop!

This is a random encounter that replaces Brad, the first Sorrow boss at the end of the first set of levels.

He is similar to Brad but has faster attacks and has eye lasers instead of a few of Brad's attacks.

I died my first attempt and the next attempt was also Barnaby.

I think I was about 15-20 attempts into this game when I ran into him.