If you don't have the Silverglen Waypoint Portal, teleport to the Cyseal-Silverglen Waypoint Portal and head North into Luculla Forest.
Head East from the new portal and you will run into a fleeing Immaculate called Samid. Exhaust all dialogue options to receive Infiltrating The Immaculates and a marker on your map pointing to The White Witch's Cabin.
Head North and East at the fork into Silverglen village. The Silverglen Waypoint Portal is just to the north of the village entrance.
Speak to Arhu in his cat form and enter the chapel next to him.
Speak to Loic in the chapel. Exhaust all dialogue options to receive Book Of The Immaculates I. You will also need Book Of The Immaculates II to prepare for the test or simply read on for the answers. The 2nd book can be found in Nadia's shop (either steal it, purchase it or complete The Naked Truth to acquire it 'lawfully').
Speak to Loic and take his test. The answers are 1-2-1. Be sure to speak to Loic and receive his blessing. He should disappear in a puff of smoke.
Head West from Silverglen, past the Silverglen Waypoint Portal and then North to the Immaculate camp. They should speak to you to tell you you cannot pass. If they don't initiate the dialogue yourself or they will attack you if you try to proceed. Tell them you have Loic's blessing to pass unhindered, or simply kill them.
Continue past the dead troll and bridge into the area engulfed in a sandstorm. Head North to find the entrance to the Immaculate Trial Dungeon.
Proceed through the 3 trial rooms of the linear dungeon. The first room forces you to contractRot1 non-leathal Void Damage per Turn but you will be healed soon. If you've completed The Troll's Bounty and received the Tenebrium skill, you won't be infected. You can also avoid the infection by sending only one character to the entrance to pick the letter from the dead body and teleport right away after doing so without any delay using the pyramid shaped teleporter to your other character.
Watch out for traps in the 2nd trial room. This room is a puzzle of weights. There are 4 pressure plates in this room ranging in size from smallest to largest. You will need to place an item, or stack several items that weigh a total of 1kg on the smallest plate, 2 kg (or 1.5 kg) on the medium plate, 5 kg on the large plate and 7.5 kg on the largest plate. You can find items that have these specific weights throughout this room: a book (1 kg), a bucket of water (2 kg), the vases (5 kg), and the heavy barrel (7.5 kg). The pressure plates will click when you've hit the correct weight.
The next puzzle requires you to position 3 levers in a specific way before triggering a fourth lever. From left to right, the three levers should be positioned right-right-middle. This solution can be found on a wall in the Northwest corner of the room.
Note: You may want to position the levers incorrectly at least once before activation as this will summon a hostile level 13 Shadow Woebringer who drops decent loot. Every subsequent incorrect activation will cause 25 air damage.
The Woebringer uses Aerotheurge magic and will also summon level 13 Shadow Wanderers to assist.
Continue through the newly opened door and you will find a Star Stone that cures you ofRot1 non-leathal Void Damage per Turn .
Proceed further until you find Loic. Loic will ask you to sacrifice the chicken running around the room, but will leave abruptly, puzzled that you have been cured of Rot. It may be better to speak to the chicken beforehand (and for a trait choice between +1 Heartless and +1 Compassionate) as Loic will return with his thugs shortly.
Kill Loic and his goons when they appear to resolve the quest (3900 XP + 6825 XP for killing Loic, +13000 XP for his goons). Continue on to discover the portal they came from (3900 Exploration XP). Alternatively, if you have pickpocketed his key for the door, he will be unable to leave the room and simply stand next to the door, waiting for someone to unlock it for him. If you approach him, he will attack you, and you can now fight him without his goons to end the quest.