Mythrilhorn - Act 2 Side Quest
Location: Northern Plain of Tears
Closest Portal: Northern Plain of Tears
Objective: Protect Khartos while he summons the Mythrilhorn
Reward: Can recruit Mythrilhorn and Loot + Gold
Mythrilhorn is a Side Quest that begins by speaking with Pet Seller Galeron in the Aman'lu Pet Shop. Much like with the Dire Wolf Side Quest you'll need to ask Galeron about a 'special pet' to begin the dialogue for this quest. Despite being able to accept this Side Quest at the start of Act 2 you won't be able to do anything until you reach Act 3.
For the first task in this quest you'll need to speak with Khartos in the town of Kalrathia (Act 3). He'll challenge you to a fight which you will easily win since he has almost no HP, after which he'll agree to help you summon the Mythrilhorn. Again, much like the Dire Wolf Side Quest in Act 1 you'll need to visit a Rift Site (this time in Northern Plain of Tears) and protect Khartos as he summons the Mythrilhorn.
You'll find the Rift Site that we need to visit in Northern Plain of Tears, just a bit north of the Teleporter. Speak with Khartos here, defend him from the 10 Durvla which come out of the portal then speak with him one more time to update your quest. All that will be left after this is for you to return to Aman'lu and speak with Pet Seller Galeron again to complete the quest.