lets say we have an theroetical player who wants to play an centaur in an ravnica based campaign. He or she chooses that they will be associated with the selesnya conclave, an spiritual guild dedicated to nature and community. Seeing as to how their race lends themselves to an more martial role and wanting to take advantage of the spells granted by his or her guild, they choose to play a paladin. The centaur player goes on to have quite a few adventures, leveling up until at last at 3rd level, the time has come for the paladin to swear an oath. The player decides to swear the oath of the ancients, since that oath is the most aligned with nature as a whole, and this proves to be an big mistake:

for you see, lets say this theoretical player is ambushed by foul fiends from another world, and so they decide to use channel divinity: turn the unholy, and so thus all fiends and fey within 30ft of them who can hear them must make an wisdom saving throw or be turned, and that is when they realize that they themselves are a fey creature, and so they too must make the saving throw and i must ask, how will this affect them?

the rules for the condition states that no turned creature can willingly move within 30ft of you, they can only use their action to dash or to attempt to escape some sort of effect, but here is the problem: it is completely impossible for you to move to a spot that is not within 30ft of yourself, you are always within 30ft of yourself no matter were you stand, like what happens now, are you just competely immobilized? unable to do anything, becuase you are too afraid of... yourself?

also similarly, if an cleric turns into a vampire or an revenant, and they attempt to use turn undead, could the same thing potentially happen?

also while we are on the topic on centaurs, if an shepherd druid who is at least 6th level casts an spell that teleports or summons an centaur PC to an location, will that centaur PC benefit from the mighty summoner feature according to RAW, and if so for how long?

The way Turn the Unholy is worded it looks like it does not target the caster even if the caster is of the correct type.  Same goes with Turn Undead and any other Channel Divinity turning effect that targets a radius around the caster.

I'd further say that a Centaur PC could not be summoned by a Shepard Druid since summoning spells summon an average member of the summoned creature's race and PCs are exceptional individuals rather than average.

it says all creatures within 30 ft who can hear you, you are able to hear yourself, youare a fey and you are within 30 ft.

and i dont mean spells like conjure fey and conjure woodland beings, i mean spells like misty step, teleport etc, depending on how you define how "summoning" you might argue they "summon" somebody somewhere, yeah proably they meant that any spell that uses the word "summon" in the desctiption, or in reality they meant spells that summon creatures, but arguably

 I was always confused by the fey unfriendly nature of 'turn the faithless'.  Certainly an ancients paladin would be more likely than other paladins to have fey allies?  Thematically their found steed is probably fey at the very least.  Like, sure, there are hostile fey that would be their enemies, but there are plenty of fey they should be playing peacemaker with, no?  As a DM I've always been inclined to houserule the ability to affect 'fiends and aberrations' instead of fiends and fey, since fiends and aberrations are both inherently hostile to the natural world in a way that fey, even hostile fey, generally aren't.

But that's house rule territory.  By raw, yeah, far as I'm reading it a centaur ancient paladin would turn themselves.

Quote from Sception >>

 I was always confused by the fey unfriendly nature of 'turn the faithless'.  Certainly an ancients paladin would be more likely than other paladins to have fey allies?  Thematically their found steed is probably fey at the very least.  Like, sure, there are hostile fey that would be their enemies, but there are plenty of fey they should be playing peacemaker with, no?  As a DM I've always been inclined to houserule the ability to affect 'fiends and aberrations' instead of fiends and fey, since fiends and aberrations are both inherently hostile to the natural world in a way that fey, even hostile fey, generally aren't.

But that's house rule territory.  By raw, yeah, far as I'm reading it a centaur ancient paladin would turn themselves.

 Hags are fey, so it is a useful ability.

this post quickly went from "what happens exactly when you turn yourself" to "can you even turn yourself also what is up with oath of ancients design in general". anyways y'all notice how this effect will actiually remove all illusions and shapechanging from an affected target, making it good for finding rakshasa, succubi, arcanoloths and other fiends with the abillity to hide, combined with moonbeam and oh well it will be good

Well, if you turn yourself you can't move closer to yourself, which is already impossible, so unless you're an Echo Knight multiclassed with the Ancients paladin, not much happens.

Quote from LeviRocks >>

Well, if you turn yourself you can't move closer to yourself, which is already impossible, so unless you're an Echo Knight multiclassed with the Ancients paladin, not much happens.

 well yes but you also cannot willingly move to a space that is within 30 ft of you, right? would that not mean complete immobilization, or being forced to move at least 30ft with every move?

Well, you can't move farther away from yourself, so I think you'd just have to stay in the same place that you stand in.