Could not target player when dueling (world pvp)

[AnyaYadai]

There was a spriest camping a player, so the player asked for help in global chat. My husband (warlock destro) and I (shadow priest) joined a party to help him.
We killed the players who were camping.. but one of them, a spriest whispered my husband in an alliance account and asks him 1 vs 1. Seems fair I thought, so I watched through his screen. Of course me being a spriest know that my husband was going to defeat him xD but... Then a weird thing happen: my husband Could NOT TARGET THE PLAYER when dueling. I was watching his screen. He just could not target (no click, no tab). He laughs at my husband thorugh his alliance account and even knowing that my husbands was clicking shadow fury (he was clicktesting) How can he knows that? He whispers me too with all kind of insults (well,... Insults are normal in world pvp I guess)
And later, I was afk in my flying mount and the player was like levitating weird while attacking me. The other weird thing he did, was knowing the exact ubication of one of our party members... It was this spriest player afk in his mount and then suddenly going another zone, going underwater and knowing exactly where the player was.
I just have like 4 months playing WoW but never seen this before.

[Fiutolog]

With this click/tab thing, maybe he was using dispersion? While in dispersion targeting can be difficult.
About teleports seen many times that people "teleport" cause they lag or have some packet loss issue.
He could locate you by having food buff "tracking humanoid", also many players have ALT chars in opposite faction to locate your actual zone.

Seems like you met some sad guy hunting new players to enlarge his epeen.

[Frostwolf011]

It was this spriest player afk in his mount and then suddenly going another zone, going underwater and knowing exactly where the player was.

Eh? He went from zone to zone instantly? Or did it just seem like that to you?

[OhieMitzen]

There's this bug, been for ages with shadowform and dispersion interaction. I don't remember how exactly to reproduce it, but it's one way to become invisible on SP like you described.

[Disktrasa]

Priests levitating and killing people mid air is their famous party trick a lot of people do it.
Priests can also wall climb by levitating themselves and walk alongside walls, thus making their way to some really wierd places, I personally climbed mount hyjal like this.
There's a addon called "spy" that makes whatever character in your range (enemies) pop up in a box on your screen, if you then target them and set a marker over them (like star) you can se them through whataver obstacles, great for tracking players, also the food buff like Fiutolog mentioned.