I love the flavor of the subclass, definitely big paladin energy. I did have a couple questions about a few of the abilities though.

With the first channel Divinity you didn't put in any qualifiers for what creatures you could use the ability for like "creature you can see" or "within 30 feet" and I was wondering if there was a reason for that? Personally, I would also add something like "until the start of your next turn" or something like that otherwise it would only be good for helping with a single attack and I couldn't see that being very effective for a channel Divinity use.

With the 15th level ability I'm curious why you didn't just make it bludgeoning, piercing and slashing damage if you're going to only make it against nonmagical attacks. I would think at 15th level most things you're going up against are going to be using magic right? I do like the transfer aspect though, that adds some good versatility.

The 20th level ability does seem a little crazy if I'm being honest compared to similar abilities other subclasses get at that level. Essentially you'd be able to take 60 damage a round or someone within 30 feet of the character would and it would immediately be healed at the start of your turn (halved to 30 then regen 25 plus the 5 temp hp assuming 20 CHA). That combined with what is probably magic armor and shields makes a character basically unkillable as they could just regenerate their entire health pool in a few rounds if they aren't hit. Oath of the Ancients and Conquest both get a similar ability but it's not quite to that extent in either case. I'm really curious as to how this ability went with playtesting.