Victory Sword Achievement in Vampire Survivors

This will be your last achievement in the game, as it first requires you to unlock Queen Sigma. Refer to Queen Sigma (100G) for doing so. Once you have her, as the description says, you need to get 100,000 kills in a single run.

The easiest and most stressfree way to do this is to enable Endless Mode and play on one of the easier first stages of the game. This will likely take 1-2 hours though. The much faster way, assuming you're very well versed in the game, are fully upgraded, etc., is to play on The Bone Zone, where there are far more enemies. I would still enable Endless Mode just to be safe (so you don't reach the 30 minute mark and have the run end and you're not quite at 100,000 kills). During the run (whether you play on an earlier level or the Bone Zone), you can add some curses to yourself to speed this process up. Curses increase the amount of enemies, making this achievement go quicker. If you choose the Skull O'Maniac when leveling up, and/or Torrona's Box, these will add some curse to you. Additionally, you can choose the Arcana card that increases curse every level, and changes curse at set intervals. Having all three of those things together can make this achievement go by in 15 or so minutes. You'll obviously need to have a build strong enough to account for so many more and extra enemies, but the standards of evolved Santa Water, evolved King Bible, evolved Axes, evolved Song of Mana, and especially evolving Queen Sigma's starting weapon with the Torrona Box, will make this very easy to survive.