Spellspire

On each floor of the dungeon, as you play each unending level, your distance is tracked in the upper left corner. You'll need to reach 150m in a single run to unlock this achievement. Note that the achievement unlocks after your run ends (when you die) not immediately.

In order to survive long enough to reach 150m, there is a little luck involved so you don't get enemies that are resistant to your wand after the 100m mark, since they start attacking very quickly and can take quite a few words to kill. In my experience, I had great results with the Legendary wand that does health drain damage (purple heart) and don't even have it upgraded a single time, yet I've gotten to over 150m on multiple occasions. I highly recommend having an anagram solver ready with words, but I also recommend only consulting it when you don't see good word progressions or are coming up against an enemy that you know resists your wand type so you want to only hit it with long words. Otherwise, I firmly believe it's faster to just hammer in words one after another instead of taking time to type in just the longest words.

Speaking of which, save the longest words for the bigger enemies and ones that you know are resistant to your wand type. Plan accordingly for different enemy types. If the little goblins or zombies are coming up next, you can typically kill them with a single 3-letter word, so don't waste anything better on them. Likewise, spamming a bigger or resistant enemy with 3-letter words isn't effective either, so stick to longer words.

As for gear, as I mentioned, I have been using the legendary health drain wand with no upgrades and have passed 150m multiple times. I also recommend the Luminous Robe, so you regenerate health if you get hit, and then the Dark Sorcerer's Hat to do double damage with 6-letter words, which is very handy for bigger enemies.

Once you reach 150m, the achievement will unlock after you die.