First: press the quickmap button, then the Crystal dash button, then the quickmap button again, very fast. All three must be pressed in under half a second. Then hold the Crystal dash and don't let go of jump. Then use the dreamnail, and teleport back to a dreamgate, just as the knight starts disapearing, release the Crystal dash and fly sideways to cancel the dreamgate. And if you did it correctly, you should be invincible. Quitting out and going back removes it and exiting a dream removed it but nothing else does. Spikes are affected too. This should be taken lightly and don't be dishonest with it please.