Please be advised that there may be spoilers in this section.
Reward: The Daichi
To unlock this tomb you first have to complete the quest "Cullis Gate", after completing that quest Brightwood Tower will come up for sale, you do not have to purcahse this Tower to start Archon's Knot Tomb.
If you meet the above requirements, head to Brightwood Tower where you will fight the same enemies as before (with Garth and Hammer). Go to the second level of the Tower where you entered the Cullis Gate, next to the Cullis Gate you will see a deviation where a statue used to be. Walk up to it and vault down.
You will dive down into some water, and behind you is a gargoyle. Proceed where you will come up to a locked gate, no worries, to your right is a slowing switch, shoot it to unlock the door. Continue and you will notice the next door seems quite unreachable. To your left is another flowing switch, shoot it and it will go towards the door.
Hit the switch at the end to unlock the door.
Follow the path up the stairs and you will notice a switch that you have to hit is locked up in a cage next to a statue, dont worry about it yet and keep going where you will find another room with spiked floors and a pressure plate. Step on the pressure plate and the statue will move, go back down and do a Bloodlust Roar towards the statue to free the switch.
Go back upstairs and hit the switch, keep hitting it and it will show you what path to take, when you get to safety hit it one more time to unlock the gate. When the gate is unlocked the spikes are no longer active so you can grab that silver key. Leave the tomb, your dog will alert you of some treasure hidden around the corner on a platform. Voila, The Daichi is in the chest there. If you want you can dive down and swim around to that island in the middle of the water, inside the building is a chest.
Reward: Sex Change Souvenir
Renown: 10000
Once you purchase the castle navigate yourself to the Regal Bed (this can be tricky) and sleep in it. You'll wake up all nice and refreshed until you are informed that your precious castle has been attacked by Bandits! Just outside of your bedroom you will encounter a small group of Bandits, kill them easily then proceed down the spiral staircase into the throne room.
In the throne room you will have to single handedly defend yourself from a few waves of Bandits, this was suprisingly easy, seeing as how they're trying to takeover your castle. After defeating the Bandits in the throne room you will have to make your way to the library to kill their leader.
Of course you get to the library you'll see that the Bandit Leader is not alone, there is a handful of Bandits with him, but you can easily slash them since it isn't a large room. Oddly enough the leader isn't the huge guy with the cape, but he should be the one on the stairs to your left. Kill them all and your whiny butler will quit, leaving you to investigate the tomb on your own.
It's worth noting that once in the tomb that you will encounter Bandits, but when you make your way to a room with prisoners walk up the the door ahead of you a pull the lever on your right. The lever on your left will open the doors and you'll have to fight a bunch of enemies at once. In the next area you will have to fight Hobbes down a few flights of stairs, there aren't all that many of them so there should be no challenge for a noble hero like yourself. Before you go down the last set of stairs you'll notive a chest below you to your right. You can vault down and open it, there's 1500 gold in there.
Next you will have to dive down another level, there is a dive spot near you if you look to your right while swimming. In the next room are more Hobbes, kill them then explore around a little, there are two chests in this area. The easiest thing to do for the switch in this room is to stand adjacent to the door behind the pillar and shoot the switch, quickly shoot it a second time before it resets, then whack it as it sits next to you. The door will open after you've completed this successfully.
In this next room the switch is timed again but it isn't hard, when it is glowing pink send a spell towards it like Blades, Shock, etc. When it is yellow shoot it with a ranged weapon. The switch will go pink, yellow, yellow, yellow before it opens the door.
Upon entering the next room you will hear an announcer who will inform you that you have this one chance in the game to change your sex. It is permanent and all that jazz. I'll give you a chance to think about it while you walk around the room and open the chests. Walk up to the potion and grab it to open the door. Drink it if you want, if not no big deal.
Reward: Temple of Light Seal
Renown: 750
Talk to the Abbot in the Temple of Light, he anticipates an attack against the Temple. Return to Wellspring Cave and proceed to the spring to your left. There are lots of Shadow Worshippers here who are equipped with ranged weapons. Use your strength and will to kill them and go back.
The second spring you go to is much like the first, repeat what you did earlier and kill the enemy below the spring. When you are finished here you will be lead to another spring, this is the final one.
You'll encounter Cornelius Grimm, leader of the Shadow Worshippers. You can't inflict any damage on him immediately so focus fire at his companions. The first wave of enemies you will fight are Shadow Worshippers, kill them like before. Next you'll face off against Hollow Men, you should have plenty of experience killing these by now.
When you are done killing off Cornelius's goons he will take matters into his own hands and try to kill you himself. He isn't weak to any kind of spells in particular so rely on your strength for this one, if you slash him he should die without many problems. Congrats, you've saved the Temple of Light!
Reward: The Wreckager
The first thing you need to do is go to Bloodstone Waterfront. There is a dock right next to a ship and the Captain should be standing on it. If you did the "Evil in Wraithmarsh" side quest you fought a Banshee here. Dive off the end and the dive spot in front of you is the entrance to the Hall of the Dead.
Once you are inside, walk ahead and dive, when you hit the water there will be a path in front of you. As you go down the path you will rn into a few Hollow Men. Keep going on and the path will split, on your left is a chest with some potions. There will be a switch across from you, shoot it, then follow it and hit it. Keep following it into the dive spot, ahead will be a bunch of Hollow Men. Kill all of them then hit the switch with will. Whack it then it will hide behind a a gear thing, shoot magic at it again. Shoot it with a ranged weapon, then magic again.
It will lead you into a room with more Hollow Men, take care of them. The switch is on top of you, so go straight through the door and it will lead you up stairs to the switch so you can hit it. It will unlock the door and you get to fight a couple more Hollow Men, after you kill them proceed up the stairs to the right. The next room will have three doors, the ones on your sides are locked so go straight.
Three Hollow Men will appear, kill them and hit the switch. Now shoot the switch and turn around and use a spell against it. It will unlock the door to a chest which contains The Wreckager and a switch. Proceed through the door across from you and follow the path back to Bloodstone.
This quest is the opposite of "Defender of Light". To activate it, speak with Cornelius in the Temple of Shadows. You task is simple, kill everybody in Oakfield to destroy the Temple of Light.
Sometimes when you are attacking the town you will have a hard time finding any villagers after the majority are dead, the easiest way around this is to walk around then return to The Sandgoose, there should be a couple back there.
When you complete this quest, there will be consequences for some time if you try to return to Oakfield, you'll have to pay ~20k gold.