You can't turn into a vampire without triggering an active Clone spell.
The reason for this is that, to turn into a vampire, you first have to die. Specifically, you can become a vampire (spawn) by being bitten by a true vampire and being buried in the ground. In the following night, you rise as a vampire spawn.
Bite (Bat or Vampire Form only) [...] A humanoid slain in this way and then buried in the ground rises the following night as a vampire spawn under the vampire's control.
Therefore, to turn into a vampire, your clone cannot be mature yet. Otherwise, it will trigger once you die, preventing you from turning into a vampire spawn.
If the clone matures after you die from the vampire's bite, but before you resurrect as a vampire spawn, it won't trigger:
At any time after the clone matures, if the original creature dies, its soul transfers to the clone, provided that the soul is free and willing to return.
If your clone matures after you rise as a vampire spawn, it most likely won't trigger either. This is for a number of reasons:
- The Clone spell only triggers "if the original creature dies". Whether or not you as the vampire spawn still count as "the original creature" is debateable, and therefore up to your DM.
- The Clone spell requires the soul to be "free and willing to return". You as a vampire spawn are under the control of the vampire who created you - whether this is just physical or if it also applies to your soul (rendering it not-free) is unclear, and therefore also up to your DM.
At any time after the clone matures, if the original creature dies, its soul transfers to the clone, provided that the soul is free and willing to return.
Hence, it'll be up to your DM to decide whether or not a vampire spawn with a clone will resurrect as the clone upon death.
By the way: if you Wish for yourself to become a vampire, or if you permanently True Polymorph into a vampire (or any other creature for that matter), only the first issue applies, since you will then be a free-willed vampire (or vampire spawn, but I'm not sure why anyone would choose to be vampire spawn over being a true vampire).
It varies by type of undead.
Each individual monster's description describes whether or not it retains its soul. This can include:
- Souls without bodies: Some undead are souls. The ghost is a soul of a creature, bound to a specific place. The specter and will-o-wisp are corrupted souls.
- Bodies without souls: Zombies are just bodies animated by necromancy or the like. The spell animate dead restores a body to "a foul mimicry of life", and says nothing about restoring the soul which departed at the original creature's death as per DMG p.24.
- Bodies with souls hidden elsewhere: The lich, for example, keeps its soul separate from its body and hidden in a phylactery.
- Bodies with souls intact: The revenant is an example of an undead whose soul inhabits their original body.
- Unknown: In some cases, it's not specified.
By default, a creature's soul departs its body when it dies. Therefore, an undead's body doesn't contain its original soul unless otherwise specified, either by some rule or the DM's decision. DMG p.24 states:
When a creature dies, its soul departs its body, leaves the Material Plane, travels through the Astral Plane, and goes on to abide on the plane where the creature's deity resides. ... Bringing someone back from the dead means retrieving the soul from that plane and returning it to its body.
There are no general rules for whether intelligent undead retain souls. The general rules on undead don't clarify either. MM p.7 merely states:
Undead are once-living creature brought to a horrifying state of undeath through the practice of necromantic magic or some unholy curse.
Magic jar?
Nothing about magic jar says you have to be a living creature to cast the spell or to use it to possess a humanoid. The text does say that once you've cast the spell you can later choose to return to your "living" body, which obviously makes no sense if you weren't already living.
The two possible interpretations are:
- You can't return to a non-living body; "living body" means that you're stuck in the gem if someone murders your comatose body while you're in the jar
- You can return; "living body" just clarifies that your comatose body does not die while you're in the jar.
Since this is ambiguously worded, by the rules it's up to the DM to adjudicate this rare case.
Best Answer
You should be able to raise your own, other, body.
Clone only states that your other body is "inert and cannot be brought back to life", not that it is no longer a corpse.
The requirement for Create Undead?
So, our checklist looks something like this:
You are the proud new owner of a screaming, howling, baby clone ghoul abomination.