Infernax

Here's a walkthrough if you need it! :) But if you want a written guide:

1. Go to the far left side of Arkos Underpass, above Combbelton Cemetery.
*You'll know it's the right spot when you walk over a green platform you can jump down.*
2. Go left past the green platform to where there's a small stone ledge next to the edge of the level.
3. Stand in the far left corner against the wall, and crouch.
4. After 5 seconds or so, a tornado will appears, picking you up, and setting you down.

At the far west end of Arkos Underpass, above the exit to Combbelton Cemetery, you will find a small ledge that ends at a wall. If you see dead trees, mountains and sky in the background, you are in the correct spot. Move your character so that you are pressing up against the wall and press down on the controller to kneel for about 6 seconds.

Please note that despite what happens, you will not actually lose any lives by doing this, so no need to worry about a potential game over.

Head to the west part of Arkos Underpass, you should see a cliff. Crouch for 10 seconds at the cliff to trigger a short cutscene and unlock your achievement. This achievement is a reference to Castlevania II: Simon's Quest where you had to kneel at a cliff holding a crystal to progress in the game.