One tricky achievement, with almost no explanation in description.
To earn this achievement, all you have to do is to write "LOL" with 3 sigils (tetraminos) on one of the lastest puzzles on tower's gates.
Puzzle must be at least 6 square width x 3 square height and must contain at least 2 "L" and 1 "O" tetramino to allow you to type "LOL" on it. No need space between sigils.