The issue is you're trying to do too much with one ninja. Something with that much going for it won't get made. I would say pick two of the three things you've said (entire field healer, immune, 1st position damage dealer). Since we've got plenty of ninjas that do the last two (6p, edo minato, kurama, etc.) it might be more interesting to see like an immune field healer, or a field healer that can deal out serious damage without immunity (like 5th hokage should have been imo).