Last evening I was running through the Cave of Shadows for another time, trying to score the best possible "record" basically by cheating. Now, when you reach the end of a challenge, it shows you the following statistics:
- Your remaining hearts
- Floor reached (either 6, 20 or 40)
- Hero Mode or not
- amiibo used on which floors
- Your time
- Best combo
- Damage taken
"Combo" means the number of enemies that you kill with one charge circle of the wolf. You can get into the dozens with Stalchilds or Chuchus. You can also only use three amiibo: Wolf Link, Ganondorf and Zelda / Sheik. It seems that Sheik just counts as using Zelda. I don't have both, so I can't try, but from what I've heard, Sheik counts as using Zelda a 2nd time.
Anyway using Zelda / Sheik heals you completely. Using Wolf Link refills the number of hearts based on your best record, which is solely based on the number of remaining hearts at the end. So, if you finish the Cave of Shadows having full 20 hearts at the end, he acts the same as Sheik and Zelda on your next run.
And it only lets you save a new record, if you surpass this number. So, if you ever manage to get to an end point with full 20 hearts, you can't do better and it won't even let you save new records afterwards. The Wolf Link amiibo only seems to save the number of remaining hearts (best: 20) and the reached floor (best: 40). So, the best possible result would be 20 hearts on floor 40. All the other statistics don't matter and won't get saved, not even Hero Mode.
What does this mean? You basically just have to get to the end, heal yourself with Zelda or Sheik and then call it a record. And that's what I did yesterday.
Welcome to the age of amiibo. Hope it will end soon...
Update: It really only lets you save, if your surpass the number of hearts. So, if you get to floor 6 with 20 hearts on your first time, it won't let you save records for floors 20 and 40! Then only deleting the amiibo data is an option, which will take away its ability to heal, making it more difficult to get a high score.
Update 2: It seems that Hero Mode doesn't get saved either. I edited the post accordingly!