The combat skill
Every hero needs some means to keep them alive. There are artifacts that are capable of helping, but this still won't keep the hero alive in really big battles. It is
incredibly hard to maintain a balance between heroes that get killed too easily and godlike one-man-armies, but I'm going to make a proper attempt.
My proposal is to give every town it's own defensive skills, all with different attributes. Therefore, every hero will have it's own strengths and weaknesses and those hated immortality potions can go down the sink. The defensive skills don't have any subskills, and every hero will either start with the basic defensive skill or obtain this skill very early on. The whole thing would look like this:
Alchemy --> Armory
Basic: AC15
Advanced: AC20, half damage from missiles.
Expert: AC30, direct damage spells reduced by half.
Master: AC40, 30% dodge of attacks.
GM: AC50, adds buffer that must be eliminated first.
Archeon --> Scaling
Basic: AC15
Advanced: AC20, adds permanent stoneskin.
Expert: AC30, adds mind and fire resistance.
Master: AC40, only 10% damage taken from missiles.
GM: AC50, adds defender option, which disables retaliation, moving and physical attacking,
but reduces all damage taken by 90%.
Barbarian --> Survival
Basic: AC18, -2 damage from all attacks.
Advanced: AC25, -4 damage from all attacks, +20% HP, 30% magic resistance.
Expert: AC40, -6 damage from all attacks, learn heal spell, 50% magic resistance.
Master: AC60, -8 damage from all attacks, no retaliation, 70% magic resistance.
GM: AC80, -10 damage from all attacks, maximum damage suffered per attack is 50, 90% magic resistance.
Chaos --> Guarding
Basic: AC15
Advanced: AC20, movement within 5 yards requires double movement.
Expert: AC30, fire and lightning resistance.
Master: AC40, magic mirror.
GM: AC50, first stack to melee attack does no damage and suffers confusion.
Death --> Disabling
Basic: AC15
Advanced: AC20, all creatures attack as if they were cursed.
Expert: AC30, adds the undead and skeletal protections.
Master: AC40, stack or creature that kills the hero suffers hand of death spell without resisting.
GM: AC50, damage is split: 25% to hero, 75% to attacker.
Life --> Protection
Basic: AC15
Advanced: AC20, permanent spiritual armour.
Expert: AC30, choose one permanent ward.
Master: AC40, regenerate 30HP every turn.
GM: AC50, one guardian angel precast every battle.
Nature --> Warding
Basic: AC15
Advanced: AC20, luck +5.
Expert: AC30, option to start with anti-magic precast.
Master: AC40, HP +80%.
GM: AC50, attacker must first come within 2 yard radius before being able to iniate melee attack.
Order --> Disruption
Basic: AC15
Advanced: AC20, permanent blur.
Expert: AC30, adds chaos and archeon ward.
Master: AC40, 100% defense added when defending.
GM: AC50, first three attacks have no effect.