Unless you finished Garden key recently, in wich case you can skip next step, you prolly might need to go get the mission first. So let's head to Inferno Clan Garden !
(Forrester Gal Zean) Location: Garden of Galahad, 372 x 411
Easy one to be found, halfway between the savepoint and the Spirit Hunter that old Inferno missions rollers know very well ...
Once spoken, you should be provided a new element in mission window (CTRL+4) : Phase 2 - Test of Courage
Time to run around & kill !
Your first target is : Fortuitous Man-Lum Mord Location: Inferno Barracks, 3027 x 957
This one's living western part of this Unredeemed base. You can access this by jumping over the fault line leading to Rubi-Ka ... so make sure you can reach far enough, or rather use the bridge in eastern part of the camp.
Your second target is : Follower Eckel Wox Mord Location: Unredeemed Temple
Run all way across the zone (or use Garden's teleport and Frontier exit) toward north-east and use any Dark Hill bridge to enter the Unredeemed Temple by its staired backdoor at these coordinates :
Inferno - 3725x3415
Once inside, move north door and step inside to zone in second room, then turn right immediately and enter boss room. There, move until Prophet's altar spot and turn right again, your target should be here - all way at the back.
Your third target is : Fortuitous Man-Fes Mord Location: Unredeemed Temple
To find this one, get out boss room and cross the second room to its other upside. The target should be up there.
Your fourth target is : Hypnagogic Yutt- Chi Mord Location: Unredeemed Temple
This one is in same room, but downer in the middle of many other adds, so be careful on pulling him wisely because you can expect massive social aggro ... wich you can consider a gentle training for later steps :)
Once this one is down, you can move out Temple for now and move south (or Garden's Teleport plus Sorrow or Yutto exit) toward Misty/Dark Marshes to make an incursion into Unredeemed camp you'll find there, for next 2 targets :
Your fifth target is : Celeth Kuir ,The Custodian Location: Dark Marshes, 1768 x 727
This spider type of mob is at upper right corner from the passage you'll be entering base. Expect some adds during your entrance and around this killing spot.
Your sixth target is : Erath Suir ,The Custodian Location: Dark Marshes, 1948 x 723
This one is just east of the previous one, so you'd better use bridge to come across ; few adds are around so this should be an easy kill. After this, it's time for the final part of the quest ; run north-east again (or use Garden teleport) like earlier.
Your seventh target is : Inferno's Unredeemed Prophet Location: Unredeemed Temple
Once back in Temple's boss room as described upper, you'll first have to kill Prophet. If not up, you might have to wait 1 or 2 hours, preferably with nobody inside Temple.
After kill, an NPC (Acolyte Senior Gal Bela) will pop over remains. One team member (only !) should now initiate dialog with him : let him do his speech and then, as soon any action is available again, use the trade item downer button and pass him 6x insignias on the right panel of the window, then accept once filled. He should then start the summoning of his masters : "This is GUARANTEED to work. I have always made it when I had six of these before. Everyone ready then? The acolyte lays the insignias on the pedestal and starts chanting...". On shouting "Enter the beast!", numerous entities will be starting to pop on altar.
Your next target is : Omega Sir Vortigern Location: Unredeemed Temple
Omega quietly waits for you among many other adds with social aggro. Your best bet is to tab & pull it around entrance to protect yourselves from adds and nukes (enhancer and/or dot can help in that). Eventually, once you'd be able to finish him, the big boss of the place will pop with even more adds !
Your last target is : Unredeemed Mordeth Location: Unredeemed Temple
Now time for your final challenge. You can use about same tricks than for Omega but beware this one has more powers, bigger HP bar and tougher nukes. Be ready for a long & tedious fight !
If your team managed to kill Mordeth successfully, you'll be rewarded of the highest key available ingame :