Viewing post in Secret ending
you have the 50 virility sword and one true cockring and plug set? You should, if using best moves depending on aura, be forced to heal ~3-4 times once reaching red but still win. The best potion you make at Valdo home will also give you significant boosts that make the fight easier after you reach red once. I'll see if I can record an example later.
Edit: I highly recommend getting focus enchantment on something if getting the hits every time is part of the problem. I think I also used the heal 5 each turn.
*Spoilers*
So assuming you have access to the mountain peak, you should have gotten a brief dialog saying to check out Horace's house in feasterra. go there, click on the dog bed and you'll find a key. That key opens the plunger in "The Gents" room in the dungeon during night. This will be in the stall closets to the door. Use the plunger in Grants room on the telescopes on the wall. When you get the lens, use it on Ghart's telescope (It's on his balcony) at night and the location to the dragon will be unlocked, at night only.