Introduction:
To me part of the excitement that stems from role playing is the thrill of danger, especially life-threatening danger. After all, isn't the purpose of role playing basically to experience that which cannot be experienced, or cannot be SAFELY experienced, in real life? How many of us actually want to put our real lives at risk and in such peril as do adventurers in fantasy games? However, that sense of thrill, that adrenaline rush is only present when it is backed by the threat of actual loss. If you know your character will ultimately survive any misfortune, then there is no real thrill in a difficult situation.
In 3rd edition D&D, no death is truly permanent. While Raise Dead spells cause the loss of a level to the victim, even a victim with no levels can still be raised. And although a Rasie Dead will not function after a relatively short period of time or if the victim's body is too multilated, there are other options that remain. Resurrection functions for many years after death and requires the merest sliver of a body part to enact. True Resurrection is even mor onerous, in that it does not require even a piece of the person being resurrected and has no time limit or level cost.
Now, it is true that Raise Deads require a 9th level cleric, and they certainly do not grow on trees. Further, Resurrection and True Resurrection require some really high level people to cast. But the fact remains that in 99% of situations resulting in death, a Raise Dead will be available and suffice. Further, even if you can argue that low level characters are not worthy of such magicks and therefore are certainly subject to refusal by clerics to cast such spells upon them, once the party reaches higher levels of play they can cast these spells themselves. Once that happens, there is truly no way for any party member to stay dead.
Ths has implications for the game world. A king of a nation is an important figure. The clerics loyal to the nation would never deny the king their spells. So how, in a world of Resurrection and True Resurrection, does anyone ever commit regicide? While 17th level clerics are no doubt rare, one can certainly be called to attend to the death of a king. With True Resurrection available, there is no way the king can EVER die! And given that regicide is a common and useful plot vehicle, and given that even high level characters should have a risk of loss, something needs to be done to fix this problem.
The Solution:
In 2nd edition AD&D this problem was handled in two ways. First, everyone had a slight chance of not surviving the resurrection. While 18 CON characters had a 100% chance, a Raise Dead caused a loss of CON so that the next time they died they did indeed risk permanent loss. In addition, every character could only be resurrected a number of times equal to his CON. This meant at the very worst, you could commit regicide if you killed a king enough times. Not a great solution, but at least one that existed. In addition, there was no True Resurrection in 2nd edition. You needed some body part to effect a Resurrection. So if the assassins could dispose of the body, the king could not be raised. Finally, Resurrection cost the caster 3 years of his life. So in a sense, every time a high level cleric resurrected someone, they killed themselves a little more.
In Therra for 3rd edition, I am adopting a variant of the resurrection survival scheme. All other consequences of resurrection remain in place (i.e. you can lose a level from being raised from the dead as per the standard rules). However, in Therra, when a person dies, Mergurr (the God of Death) embraces the soul and welcomes it into the Realms of the Dead. This is a very tempting embrace, very akin to real life accounts of a bright and welcoming light drawing in the souls of the departed. The soul inherently wants to travel into the Realms and once there wants to stay within. It takes an effort to wrest the soul from its demesne. This effort is wrenching tot he soul, whcih is basically in transition from its former life to its new life, and as such this wrenching tears off a piece of the soul, thus causing level loss.
The Raise Dead spell basically catches the soul before it has entered its final resting place. Essentially, the cleric reaches into the tunnel leading to the Realms of the Dead and invites the soul back to the living. More powerful clerics can reach further into this tunnel, thus accounting for the days per level time limit of the spell. Resurrection and True Resurrection, however, actually attempt to wrest the soul from the Realms of the Dead. This is why they can be cast long after the soul has departed and why they are such high level spells.
To cast either spell the soul, on a conscious level, must wish or consent to return to life. There is no way to wrest a soul from the Realms that wishes to remain. The combined force of the soul and the Realms makes it impossible.
However, if the soul wishes to consciously return to the living, then it must still overcome the magnetic draw of Mergurr and the Realms. Mergurr's Realms signs to the soul, seduces it, and bullies it into entering its final resting place. It takes a great force of will and effort for even a willing soul to return to life. Further, each time a soul tastes of the Realms and the embrace of Mergurr, it becomes more and more attuned to it, almost addicted to it. Thus, each time a soul departs death and returns to death it becomes harder and harder to resist Mergurr's call. Eventually, all souls come to Mergurr.
The Rules:
When a person dies and is resurrected, they must make a resurrection survival roll against DC 5 modified by Wis, Con, and Cha modifiers. Once a person has been brought back from the dead, he bears what is known as the Touch of Mergurr. Each time he receives the touch of Mergurr (i.e. dies and is brought back), the DC of the resurrection survival roll increases by 1. A roll of 1 is always a failure and a roll of 20 is always a success. Thus, it is theoretically possible for someone to never die and always be resurrected if he keeps rolling consecutive 20s (of course, you can also die from old age as well).
Example:
Marco dies at the hands of a bugbear. The cleric Kelliene attempts to use Raise Dead. Marco has a Con of 15, a Wis of 12, and a Cha of 9. His DC is 5 and his check gains a total bonus of +2. He rolls a 6 and survives. A year later Marco is slain by a dragon. He has the same statistics, but this time his DC is 6. He rolls a 4 and just barely returns. Two years go by and Marco is this time slain by a dinosaur. He has the same statistics and his DC is now 7. Marco rolls a 4 which at +2 equals a 6. Marco's soul now is firmly and forever in the Realms of the Dead and Marco is slain permanently.
When a character dies and is raised, he should note on his character sheet a Feat/Ability called Touch of Mergurr and then put a +# equal to the addition to his DC of 5. Thus, Marco had Touch of Mergurr +2 as a notation before he died the last time.