Gains
Upon completion of this quest you will gain:
2550 experience (or a 12 compensation at level 70)
350 reputation with StormwindI got 2000 xp and 275 rep as Human Rogue 21lvl

i soloed this as a level 23 paladin.
first i killed all his adds with help from the fishlever oil i got from a previous quest, i also had to use loh and pot, then i just fled and rested and came back and killed Tharil'zun ^^

Try to pull the mobs around him before Tharil himself, this will greatly help you.
Also, be sure the area outisde the room is clear to avoid aggroing more than you can handle.

An easy way is to get someone who can ressurect to wait while you nuke Tharil. When you die, they res you and you can both run in and loot him then get out of there.

Solo'd him on a 27 Assassination Rogue.
Malice, Puncturing Wounds, and Lethality make for some heavy Backstab crits, so I sapped the caster near him, opened with Cheap Shot, Backstabbed, drank a Thistle Tea, got off two more Backstabs before CS expired, popped Evasion as he turned to fight me and his 3 allies swarmed me. I Eviscerated him, tossed on a few Sinister Strikes to finish the deal, and used Vanish to escape after looting his head.

This is a good quest to pair with Wanted: Gath'Ilzogg (https://vanillawowdb.com/?quest=169 https://vanillawowdb.com/?quest=169) and Shadow Magic (https://vanillawowdb.com/?quest=115 https://vanillawowdb.com/?quest=115). He's right around the corner from the castle that Gath'ilzogg is in.

Just easily solo'd this with a 29 arcane mage.

Seems easier to do if you go down and around the lake and enter from the south... You can hit the guy by the door easily and then take out the other guy to the far left in the area with arcane missile.

In normal words the place is in Stonewatch Keep, which is far east from the Lakeshire, pass the Alther's Mill. Then you enter the ""castle"" and you see the MAIN building/castle. Ignore it, keep going and you see wooden gate which is ""broke"". Behind that, in the corner, stands Tharil'zun and one of his caster.

Fellow DRUIDS there; if you are 23 or more, this guy isn't too hard, but doesn't have a chance for mistake.

First of all clean everything else in the ""space"", watch out for them! They run when low hp! After you've cleaned, there should be one caster and Tharil'zun. Buff yourself up, take full mana/health. Regrowth/Reju, and use Roots on the Tharil'zun. Go to caster, start killing him. Some point Tharil'zun will break from roots (Will break before the timer is done!). Ignore him, kill caster, pop out of cat. Root him right away, back up, bandage/reju/regrowth and go in, if he is not enraged! Everytime he gets enraged, change from cat to bear or just root him and wait. Important in catform is to put bleed on him with combos before going bear! Bring him down and be happy to again solo one elite of your own lvl. :)

P.S Watch out that net he throws, swift form and you're fine.

Siune 24 Druid, Stormreaver.

Solo'd: lv 25 warlock. Standard warlock approach: fear Tharil'zun, kill the adds, dotdotdotfeardotdotdot.

Soloed as a level 25 affliction warlock. Wait for the roaming Blackrock Sentry, kill him first. Then once inside Tharil's little room, kill the Shadowcaster on the left. Then it's time for Tharil. Send your void walker in first and make sure you attack the Shadowcaster, and take him out first, being sure to DoT him up as fast as you can before he banishes you. By the time the Shadowcaster dies, your void should be at about half health. Start DoTing up Tharil, make sure your void keeps aggro though. Then start health funneling to your void walker. Just keep those DoTs up and your void alive. You may need to sacrifice the void walker should Tharil aggro on you, but then you can just shadowbolt him to death. Should be a cake walk. :)

Easy soloable with a level 24 Demonology Warlock.
Four Mobs in close range of Tharil'zun. Two can be killed without aggroing Tharil'zun.

Send your Voidwalker to attack Tharil'zun. Wait for his first attack to hit. Then cast you DoT's on him (Curse of Agony; Corruption, Immolate).
Now cast the same DoT's on the caster, and finish it off with Rain of Fire.

By the time the caster died, Tharil'zun will be around half health. Recast your DoT's and nuke him.

He used a Net to trap my Voidwalker and started attacking me. But his health was low and after his first hit on me, he ran away in fear.

Easy to kill... Was not even close of crit health or even OOM.
Like Incurable sawowhead:1,id: ""Should be a cake walk.""

And I got the best reward you can get from him... I dinged

Soloed as a level 22 draenei paladin (talents 5-5-2, yes I know I forgot to use a talent point!). With my twink gear and given how short the fight was, I think its also just soloable at level 21 (5-5-2 again).

Blessing of Might, Seal of Righteousness, Devotion Aura switched on. Took out the lone left caster. Cast Gift of the Naaru to get the nice HoT overheal. Then just charged the other caster next to Tharil'zun, layed down Consecration immediately for the dot on both, Hammer of Justice for the stun on him (not sure if that was too effective, but it didn't matter since he didnt hit hard enough to overcome Gift of the Naaru for first few seconds). Judgement of Light and 2 auto attacks later the caster is dead. Then the level 24 elite was dead after only two and a bit rotations of Judgement of Light and auto attacks. I felt no pressure to bubble up at any time or switch to Retribution Aura to speed up the kill. He simply wasn't doing that much damage. I had 20% health left as the elite guy tried to run away, then he died...No potions of any kind necessary.

Did it as lvl 22 shadow priest, had https://vanillawowdb.com/?spell=15448 this though. Just cleared all the mobs around him and in the cort. Than nooked caster, feared boss, killed the caster and ran out to reset. And than just PWS, nook, fear, PWS, nook, finish him off. Its really easy 4 clases with fear, cause its almost like he was in a building, there is no way out. But he managed to run out once, so better watch it.