Well, there's an eye that needs to be stabbed, and another one that needs to be woken up. Because of the horn, you can't have a timeclone do those things, so you'll have to do them yourself.
This means that the timeclones are going to have to hold down the pressure plates that wake the eye. Keeping them there isn't an issue - there's an orb that will lock the timeclones in with force arrows. But timeclones can't command Halph, and hot tiles also get in the way of that.
In short, your main goal is to get the timeclones to step on those pressure plates, and use the orb to keep them there.
For a starting hint:
Click here to view the secret text
×Anything a timeclone does after stepping on a plate doesn't matter in the final recording.
Think about how you could take advantage of that.
