How I think the Dreamtale FNF mod will go (Or at least the special notes for it):
Positive notes- You can hit those notes, but they will make you lose health if you hit them while you have 100% health. Dream has these (Also Shattered in freeplay)
Negative notes- You need to miss those to avoid losing 50% of your health. Nightmare has these (Also Shattered and Passive in the freeplay)
Encourage: During "Nightmares", you can press the spacebar to get some encouragement from GF, which will make you immune to health drain for a bit. The only catch is that if you do it too much, Nootmare will catch on to it and make GF stop talking, meaning you can't use that ability anymore. (Tbh IDK how he's going to do that yet-)