Level 1:
Vigor - change the skill to add HPs equivalent to a percentage of the character's LEVEL. I.e. 1% per skill point, so a level 100 character would get up to 135 HP (fury shrine, max points himself)
Sounds good as it stands. Or even half that.
Level 25:
Evade: similar to Vigor, but affecting defense and being weaker - i.e. 0.05%*hero_level bonus to defense per skill point.
Rockskin: the same, armor
Or turn them around: 0.05%/level for Vigor and 0.1%/level for each of these. Works either way. Though I think you meant Fortify, not Rock Skin....
Level 75: Absorb and enchant armor as they are now.
Only thing I'd say about that is that very few people ever develop Absorb... there are simply more useful skills out there. It's not useless, just usually not worth it when compared to other skills available. Well, that, plus Absorb is actually L25, not L75, but that's a minor detail.... :wink:
Rock Skin: follows the pattern above. If Fortify/Evade provide 0.1%/level, then Rock Skin provides 0.05%/level to both armor and defense. Or else do something completely different—base it on an enhancement rather than a stat: say, doubles the effectiveness of Reinforced Armor (your armor is increased 50%) if the enhancement is triggered? Or doubles the chance of it triggering?
Level 150: Get rid of aura of protection, replace with two new skills
Skill Name: Parry - when opponent misses in his attack, cause some damage to him... probably a percentage of his own damage roll.
Skill Name: Crown of thorns - counterpart for Parry. If the attack scores only 1 damage, part of the absorbed damage is inflicted upon the attacker.
Not bad ideas... though we already have enough skills to spend points on lol! Maybe just one of these... probably Parry. Though you could also express this as "Riposte"—in which case the damage done should be a percentage of your own damage, not your opponent's. "Parry" really ought to just give you a better chance to avoid damage (i.e. increase opponent's chance of missing... say, add a percentage of your attack score to your defense score?).
I like the Crown of Thorns concept, but it might be better if the opponent takes damage whenever the buff reduces it, no matter how far it is reduced (say, 0.1%/level chance that the buff reduces damage
and returns that damage—or part of it—to the opponent... could give us "double kills"

).
Note that by expressing these as "opponent" rather than "attacker," you make them useful in normal combat, not just PvP combat... since
you are the attacker in normal combat. This won't matter if you're one-shotting critters, but it will make a difference whenever they get to hit back at you.