The boss moves around the room; bouncing up and down while the only attack it has is the Kegerator shots spilling out from the top. Mines do spawn from the shots, but disappear over time.
In the single version of this boss fight, spinbots and bombbots can spawn at various locations.
Single: As long as you maintain damage per second on the Snow Globe Bro in the single version and constantly move around you should have an easy time beating the boss. If too many adds spawn you may want to divert attention to them as the actual boss isn't a big threat.
Double: Take down one Snow Globe Bro at a time as it will decrease the amount of mines you will have to deal with in the boss fight. Once one is down the rest is easy. Keep moving and try to attack from a distance if possible as the Snow Globe Bro's shots most of the time don't travel a lot of distance.
The mine mod or Kegerator can make this boss fight a problem as there is no way to discern which mines are yours and which are the Snow Globe Bro's.