Brotato

To unlock this achievement, you'll need your loadout that has your damage percentage high in the triple figures, an attack speed close to 100%, as well as bare minimum a decent critical rate. You'll also want to prioritize on characters with unique perks that will help boost your damage rate further as well as weapons that can do the same.

How I got this achievement was by picking Fisherman, due to his perk of having the Bait item always offered in the shop at the cost of just one material each, with each Bait boosting my damage rate by 8%, and it can be offered again with rerolls before starting on the next wave. I also stuck with just the Stick, on account that each additional Stick in my weapons set boosted my overall damage. I boosted my damage solely from using the Bait item at least three times before each wave, focusing my investment in level ups and items boosting various healing (HP regen, Life Steal) and defensive skills (Armor, Dodge, etc.) and buying any additional Sticks that became available. I was able to get my damage rate to over 400% with a 81% attack speed and a critical rate of 19%. I upgraded HP regeneration to 22, with Life Steal at 2%. For defensive skills I set my Armor at 13, and my dodge rate at 42%.

I found this easy with Bull and the following stats

• Level - 11
• HP - 51
• HP Regeneration - 46
• % Life Steal - 1
• %Damage - 0
• Melee Damage - 24
• Ranged damage - -6%
• Elemental Damage - 2
• % Attack Speed - -3%
• % Crit Chance - 0
• Engineering - 0
• Range - 0
• Armor - 10
• % Dodge
• % Speed - -2
• Luck - 0
• Harvesting - 0

With these stats and just walking into the elite that spawned on Danger 2, Wave 11 he was dead in less than 5 seconds and I had the achievement. Hope this helps.