Here's an idea. Ya know those pesky rocks that fall from the mountains... and some of us use those in custom boss battles? They do a measly half heart damage. How about a "Lv2 Rock" that does 2 hearts of damage, or something so that you would actually TRY to avoid them? I know if I had 8+ hearts and blue ring, I really wouldn't mind getting hit by the rocks... so I don't bother avoiding them too much.
Tougher Rocks!
I think the little rocks should just harm you, and disregard what ring you have on, and the bigger ones should should kill in one hit. Quest rule, of course