Can the lava golem be damaged without using a serious bomb?

I just defeated the lava golem by combining Serious Damage and Serious Bomb. That felt cheap, but in my previous attempts this battle seemed otherwise simply impossible, as the health bar of the golem didn't seem interested into nudging one bit.

Even just the serious bomb alone isn't enough: it brings the boss to 25%, and then gets you swarmed again in short order.

Can you earn your victory without resorting to a serious bomb?

This link specifically refers to the Random Encounter boss fight, and suggests using Serious Damage and a mini-gun to finish him off.

So yes, you can defeat this enemy without using a serious bomb.