Just to be clear, the Thrall player is dead, right? They cannot do anything, so they should just be dead.
Also to word the Enthrall so it doesn’t convert death immune targets (would be awkward if you could actually kill the MM through this by making him a thrall).
"Attack target player. If they die, you raise them as a thrall.
For a neutral killer this one doesn’t hold much power over the court unlike Reaper and Possessor. Sorc got a “get-out-of-jail” card that is a band aid to assist late game, but is easily countered by Prince or Butler as there is no one else with this particular mechanic aside from King (and it’s often easy to discern).
You have Puppet to make your Thrall clear you, but considering you know this mechanic exists, if you or your Thrall ever gets suspected, the Court may just exe your Thrall, they flip Thrall and then they know to jail-exe you, given you are singled out through other info.
You do get to vote for them, but does that give you access to both accusation and trial vote?
Let me suggest a few changes that could be interesting to play around with.
Remove Desecrate. The ability seems a bit like a tack-on that doesn’t really fit. It’s just to make some chaos by implicating the existence of either Herbalist/Possessor/Vampire. Unlikely to throw suspicion off you.
Changes to Enthrall: Instead of Thralls dying the next night, let them stay until replaced by another Thrall.
Changes to Command Thrall: Attack two target players, your Thrall/Familiar commits suicide at the end of the night. Requires a Thrall/Familiar to be used.
Familiar: If you are executed on trial, you will take the spot of your Familiar, if you have one. If you have a Familiar, Enthrall will kill the target and not replace your Familiar.
Dark Ritual (inf uses): Prepare a ritual to make your Thrall into your Familiar at the end of the next night. For this night, Enthrall will not raise the target as a Thrall to replace your existing Thrall.
This means the Vampire has a defense in Court they have to set up. But the Vampire needs to keep the Familiar from getting executed or they lose their shield for 1-2 days, so they need to use Puppet to make the Court trust them.
If a Familiar gets executed during the day, the Vampire will need to Enthrall a new target the following night (and not get blocked - OCC’d/jailed/target healed or delayed) and use a day ability to set up the shield - at which point Court might execute the new Thrall or you, and first at the end of that next night, the Familiar is a shield.
If a Familiar gets attacked during the night, it’s even worse as the Vampire has to dodge through 2 days of trials before their scapegoat is ready at the earliest.
So it is a very powerful defense, as it essentially grants you another life, but it does require some setup and have risk of getting killed by Cultseen/Prince/Alch/Inq/Court/Knight.