Risk of Rain 2

This will almost assuredly come naturally during either the Simulacrum DLC, if you buy Survivors of the Void and use the build I recommend, or during your run for The Long Road (30G), if you use my recommended build there. You'll be outputting absurd amounts of damage, but to sum up the items you should be aiming for:
 

• Lens Maker's Glasses - get 10 stacks to give yourself 100% chance to crit (every attack will deal double damage). Beyond 10, these have no effect, so no need for more
• Crowbar - extra 75% damage to enemies at full health, so these stack up very fast
• Missile Mk1 - these are incredibly strong. Each stack increases their damage by 300%. I recommend stacking these as fast as possible, because a single missile will be doing massive damage

Stacking those are enough to get this achievement only a few stages in.

Note: it should go without saying, but you should be using the Artifact of Command (and Artifact of Sacrifice) to make this achievement so much easier by eliminating the RNG aspect of getting the items you want. Refer to the roadmap for an explanation on unlocking these artifacts.