Shadow Priest-Do Millions Of Damage And One-Shot Things (Patreon)

The shadow priest honour talent "Psychic Link" allows a player who has cost Mind Blast and Void Bolt to deal 30% of their damage to any player affected by Shadow Word: Pain. If you attack a low-level mob in low-level areas when a high-level mob/player is affected by Shadow Word: Pain then this will do an insane amount of damage due to the damage multiplier that affects attacks against low-level mobs.

The practical applications of this are interesting,

1) You can win any duel with it.

2) You can kill anything in world pvp by targetting the plentiful supply of critters scattered around the world.

3) You can target any mob while in pvp combat and kill anything with it while in a low level zone.

4) You can target low-level items such as player flags  in instanced pvp for this purpose.

5) (Speculative) If you can find a "unknown zone" in  a pve instance then you can  duel another player and (at least in theory) use this against pve mobs/bosses. Some bosses have teleport-to-boss abilities which may make this viable.

You can test this out with the training dummies in your faction's capital city: put Shadow Word: Pain on a pvp dummy. Target a low-level dummy and use Mind Blast-you'll see damage in the millions on the pvp dummy from psychic link.