Immortals, 5E Style
by Blacky the BlackballLet's use Dark Dungeons Immortals as a starting point (because why not) and then introduce some Gold-Box-isms.
The Immortal character class (there's just a single class) has 20 levels just like the mortal ones do. However, instead of starting at 0 XP, a first level Immortal starts with 300,000 xp (this is a tenth of the Dark Dungeons amount, because xp requirements in 5e are much less than in BECMI in general). This means that it's possible to achieve Immortality towards the end of level 18, or at level 19 or 20. The class will have a pool of Power Points (PP) at each level equal to a thousandth of the xp needed for that level, rather than a ten-thousandth, so that the PR remains in line with the BECMI versions.
By default, Immortals are intangible spirit beings. We'll consistently call this spirit form "intangible" rather than "incorporeal" so that it doesn't accidentally interact with any other rules or spells that affect incorporeal creatures. Immortals in spirit form are immune to everything except power attacks and probes (both of which are Immortal level spells); but the only ways they can interact with the world are:
1) They are visible (either as a ball of light, a glowing translucent version of one of their avatars, or a glowing version of their holy symbol), and have an aura that they can use to scare or awe mortals.
2) They can travel freely through any substance, unharmed and unimpeded. However, this also means that they can't interact with any substance in any way (e.g. picking up objects).
3) They can fly at a varying speed (the exact speeds will depend on seeing relative speeds of things in the 5e PHB and MM).
4) They can speak and read all languages, and can communicate by telepathically speaking to one or more creatures in 100' (including other Immortals in Spirit form).
5) They can use mortal level magic (if they've spent the PP to do so) but only travel spells. They can also use the Power Attack, Probe, Detect Immortal Magic, and Probe Shield spells (all of which are Immortal level spells).
Combining the rules for physical form (or "manifestation forms" as WotI calls them) and the rules for avatars, we get the following:
An Immortal can create one or more Avatars for itself. An Avatar is a potential physical form that is much tougher than a normal mortal body. It costs an Immortal 10,000 xp to make an Avatar, so they are not made on a whim. The Immortal decides on the physical form of the Avatar when it creates the form, and this physical form can have a number of Avatar Powers (I'll come back to these in a later post). As an action, an Immortal in can pour some or all of its PR into an Avatar, causing it to appear as an actual physical form.
If the Immortal has only devoted some of its PP to the Avatar form, it appears as a Lesser Avatar next to the Immortal's Spirit Form and both exist in parallel. If the Immortal gives all its remaining PP to an Avatar form, it appears as a Greater Avatar replacing the Immortal's Spirit Form in its location.
An Immortal can give power to as many Avatars as it has in this way, in order to be in multiple places at once. However, each Avatar can only be in existence in one place at once (but there's nothing to stop an Immortal from creating more than one identical Avatars - or even Avatars that look identical but have different Avatar Powers - if it has a favoured form that it prefers to appear in). Note that the difference between a Lesser Avatar and a Greater Avatar is in terms of investment, not in terms of the amount of power. A first level Immortal with 300 PP and two Avatars could pour 200 PP into one and then the remaining 100 PP into the other. It would then be inhabiting two simultaneous bodies - a 200 PP Lesser Avatar and a 100 PP Greater Avatar.
A Probe spell can tell whether an Avatar is a Lesser or Greater one, but mortal level magic is not capable of distinguishing between the two.
An Lesser Avatar that has used up all its PP winks out of existence, and a Greater Avatar that has used up all its PP turns back into the Spirit Form of the Immortal. If the Spirit Form or Greater Avatar of the Immortal is present, it can withdraw the remaining PP from a Lesser Avatar by touch, effectively dismissing the form and re-gaining whatever PP the Lesser Avatar had left. Similarly, a Greater Avatar can dismiss itself at will, turning back into the Spirit Form, retaining all the PP it has.
All Avatars have separate minds for the purposes of mind-affecting powers or spells, but the minds are in constant sub-conscious contact and all have the full knowledge of all other Avatars of the Immortal and they also share this knowledge with the Spirit Form. Whatever is experienced or learned by either the Spirit Form or any Avatar is instantly known to all of them regardless of distance.
If the Spirit Form of an Immortal has spend PP to gain spell casting abilities, these PP don't affect the Immortal's Lesser Avatars - they must also spend PP independently from the ones given to them. However, the spell casting abilities do move over to the Greater Avatar of an Immortal. Also, each day when an Immortal regains its PP, only the Spirit Form or Greater Avatar regains PP. it doesn't regain any that are currently in Lesser Avatars, and neither do Lesser Avatars regain PP.
For example, our first level Immortal is currently in two bodies - a 200 PP Lesser Avatar and a 100 PP Greater Avatar. If the Avatars spend 50 PP each on various abilities, they will have 150 PP and 50 PP respectively. At the start of the next day when the Immortal regains its spent PPs, the Lesser Avatar will regain nothing. It will still have 150 PP. However, the Greater Avatar will regain all PP that are not currently in Lesser Avatars - in other words it will regain the hundred that have been spent in total and will now also have 150 PP (its normal total of 300 minus the 150 that are still in the Lesser Avatar).
The physical attributes of an Avatar are based on the level of the Immortal, regardless of the number of Power Points that it has, and any Avatar can spend xp on greater Immortal level spells with the total coming off the Immortal's experience total.
That all sounds a lot more complicated than it is. In practise, the majority of Immortals rarely bother with Lesser Avatars, and simply transfer all of their life force into a single Greater Avatar most of the time, not bothering about the complication of being in more place than one at once.
Avatars (regardless of whether they're lesser or greater) have the following abilities:
1) Avatars have the same aura as Spirit Forms.
2) Avatars are completely immune to mortal-level magic, and are only harmed by the most powerful of mortal weapons (I'll have to wait for the DMG to work out what these weapons are). Even then they take minimum damage from such attacks. Avatars are hurt by Immortal-level opponents normally.
3) Avatars have very strong resistance (I'll have to wait for the rules to work out how this should work) to Immortal level magic.
4) Avatars are immune to all natural damage (e.g. fire, cold, poison, acid, etc.) and need to neither eat, drink nor breathe. An Avatar could happily fly casually through the sun without being unduly affected by the pressure, gravity or temperature.
5) Avatars can cast all Immortal level spells, and can spend PP to cast mortal level spells. The other abilities of classes (e.g. turning undead; fighter abilities; rogue abilities) are acquired as Avatar Powers. I'll have to wait for the PHB to be able to determine where the split should be between what's gained temporarily by spending PP and what's gained permanently as Avatar Powers.
6) If an Avatar is physically killed, the Avatar is destroyed permanently. A Lesser Avatar will simply vanish on death. A Greater Avatar will vanish and be replaced by the Spirit Form of the Immortal. In either case, the Immortal can no longer use that particular Avatar (although they can create an identical one at the same cost, of course).
Immortals can also create Mortal Forms. A Mortal Form is like an Avatar in that it is a potential form that the Immortal can inhabit, except that it is cheaper but not as tough. Mortal Forms only cost 5,000 xp to create. Unlike Avatars, Mortal Forms neither have nor use PP and an Immortal can't inhabit multiple Mortal Forms at once. An Immortal can switch to a Mortal Form from either a Greater Avatar or its Spirit Form, but not from a Lesser Avatar. Because of the limitations of a Mortal Form, if an Immortal has any Lesser Avatars at the time it switches to a Mortal Form those Avatars disappear and their unused PP return to the Immortal.
Mortal Forms are completely undetectable as being Immortals by any means. Any and all types of detection or divination (including Immortal level spells) will simply show them to be normal mortals. Not even mind reading effects will reveal this, since the knowledge that they are Immortal is hidden. This makes Mortal Forms ideal for any time an Immortal needs to go "undercover" and not be detected by rivals.
However, a Mortal Form has all the vulnerabilities of a normal mortal body and can't use any Immortal level spells or abilities other than the ability to switch back to a Greater Avatar or a Spirit Form. If a Mortal Form is killed, the Immortal will automatically revert to its Spirit Form. The Mortal Form is permanently gone, although as with Avatars, the Immortal can create an identical one if they like.