If Hit Points are a measure of skill level, luck and other factors, in addition to raw ability to withstand injury, it makes little sense for healing to repair proportionately less damage to a character with lots of HP. The system below also helps to negate the increasing need for parties to be loaded down with healing potions and spells as they gain in levels.
Spells and their equivalent potions will always restore at least a minimum number of HP; see the table below. Additionally, any Curing magic will restore lost Fatigue.
As the amount healed by Lay On Hands already increases when the caster improves in level, it's not affected by this system.
Round to the nearest HP when calculating healing. Note that non-lethal damage naturally heals completely in 30 mins; any magical healing also restores all lost non-lethal damage.
The ability to Turn Undead is an homage, of course, to Dracula and various Hammer Horror-style films where an intrepid priest uses a cross against an unliving foe. It has occurred to me that the AD&D version is a little colourless and lacking, resulting in either a set of fleeing undead or nothing at all. Here's a reworked system that also allows for an intermediary result much like that Van Helsing usually managed; an undead foe held at bay, neither fleeing nor unaffected.
Base roll is 2d10, rolling to equal or beat the value in the table below. A success affects 2d6 + Priest's level in enemy HD, starting with the lowest HD undead present. Evil or necromantic-style priests will compel the undead into their service if they roll well enough. Alternatively, evil priests can hold, turn or destroy Paladins and good-aligned supernatural creatures.
| Level of Priest | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Undead Type | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8-9 | 10-12 | 13-14 | 15+ |
| Skeleton | 8 | 6 | 4 | 2 | 0 | -2 | -4 | -6 | -8 | -10 | -12 |
| Zombie | 11 | 9 | 7 | 5 | 3 | 1 | -1 | -3 | -5 | -7 | -9 |
| Ghoul | 14 | 12 | 10 | 8 | 6 | 4 | 2 | 0 | -2 | -4 | -6 |
| Shadow | 17 | 15 | 13 | 11 | 9 | 7 | 5 | 3 | 1 | -1 | -3 |
| Wight | 18 | 16 | 14 | 12 | 10 | 8 | 6 | 4 | 2 | 0 | -2 |
| Ghast | 20 | 18 | 16 | 14 | 12 | 10 | 8 | 6 | 4 | 2 | 0 |
| Wraith 1 | 20 | 18 | 16 | 14 | 12 | 10 | 8 | 6 | 4 | 2 | |
| Mummy 2 | 20 | 18 | 16 | 14 | 12 | 10 | 8 | 6 | 4 | ||
| Spectre 3 | 20 | 18 | 16 | 14 | 12 | 10 | 8 | 6 | |||
| Vampire 4 | 20 | 18 | 16 | 14 | 12 | 10 | 8 | ||||
| Ghost 5 | 20 | 18 | 16 | 14 | 12 | 10 | |||||
| Lich 6 | 20 | 18 | 16 | 14 | 12 | ||||||
| Minor Demon 7 | 20 | 18 | 16 | 14 | |||||||