1. Upon returning to Camelot Castle, Merlin instructs you to find Darren's and Lug's keys in the area surrounding Crownhorn Village. Go to the Round Table and put those two knights in your party. Now, there's something you need to know about this quest: A giant boulder in the region around Crownhorn has made all the warlords invincible. Therefore, the key to this quest is to be clandestine - there are ways of sneaking around the clusters of warlords that patrol certain areas and you'll want to avoid them at all costs. If you do confront them, you will not be able to kill them or leave the screen, and thus allowing them to kill Arthur so that you automatically return to Camelot is the only way out.
Aside from that, there is another reason to be careful about not confronting the invincible warlords - There is a HIGH probability that the game will CRASH if you do. Sometimes, it will freeze, sometimes the screen will go blank, sometimes Arthur becomes stuck in place and although he can still swing his sword and turn to face different directions, you can't actually move him from that spot. I've even seen a scenario in which the warlords began wandering around aimlessly as though they could not figure out where I was. Because I couldn't get them to kill me, and I couldn't kill them, I could not leave the area and thus had to reset to get out of it.
2. Use your map to warp to the farthest possible spot northwest that you can go (shown in my first screenshot.) Leave the screen you arrive at going north and then turn west and go through the first set of gates you come to. This will put you in Crownhorn Village.
3. Go south through Crownhorn's gate, then immediately start going west, past a church, and keep going until you reach a small house that you enter through the side (shown in my first screenshot). Talk to the woman inside the house. She requires three items to help you break the boulder. Note that if you have trouble finding stuff in Crownhorn Village, you can visit the Maps Page for help.
4. Leave the house and start walking in a general southeast direction until you end up at the south part of the gate surrounding the village. Walk along that wall until you find a small building that you enter from the side (first screenshot). Go inside. You will find Lug's Key of Truth in there. If Lug is in your party, he'll grab it and you'll warp back to Camelot.
5. Go back to Crownhorn Village exactly as I had instructed you before, and go south through the gate again. But this time, once inside the gate, walk back towards the righthand wall. Go south along that wall and keep going until you see a stable-like structure with the very tip-top of a shield poking out from the back of it. This is Trunk's Shield. Grab it.
6. Go west until you see the south exit from the town's gates. Go through it and take the path going west. Leave the screen going west and you'll be in the Pixie Forest. Walk up to the northwest corner of this screen, and you'll see the Pixie Dust lying under a tree. A huge swarm of fairy enemies will come out of the trees to attack you, so kill them all and then grab the dust.
7. From where the Pixie Dust was, go south until you see a path going west offscreen and take it. You'll be in the rocky mountains area. Start going south and go off the screen. From this screen, immediately start going east and you'll eventually see a shield sitting amongst the trees at the VERY top of the screen. This is Zeke's Shield. Get it.
8. Turn around and go back to the left and keep going ALL the way until you're up against the trees at the west end of the screen. Start going south until you see a shiny red object on the ground. This is the Mordraine Wood. Get it and immediately turn around and go back north to the top of the screen again. WARNING: Absolutely, under no circumstances, go any farther south than the Mordraine Wood for now! There is a group of invincible warlords beyond that point, and if they spot you, the best that can happen is that you'll be killed and end up back at Camelot...the worst is that the game will crash and you'll have to reset.
9. Go back one screen north, then back one screen east so that you're in the Pixie Woods again. Walk all the way to the right side of the screen, then go all the way up and leave through the top of the screen. (Note that if you hug the trees on the right side of the screen, you will not have to encounter those fairies again.) Follow the trail north and when it forks, take the lefthand path going north. Do NOT go to right side of this screen!! There is another group of invincible warlords over there that could kill you or crash the game! Keep following that lefthand path north and leave through the top of the screen again. You're at a broken bridge. Step onto the bridge and Arthur will fall in. Try to avoid the rocks as you float downstream because they will cause some damage. When you go over the waterfall, allow yourself to get sucked down the whirlpool and you'll be in an underwater cave.
10. Walk to the right and cross the little bridge to the other side of the water. Take the first passage going south, then follow the path south, then right, then up. You'll find the Saltmoss at the end of the tunnel.
11. Leave that room and keep going right, then go south through the next passage. Wally's Shield is in this room. Grab it, then leave and exit the underwater cave through the right end of the screen. (Alternately, you could stock up on some Shield Orbs and Healing Herbs in the caves on the north shore of the river before leaving, if you need them.)
12. Arthur will be alone on the overworld. Warp back to Camelot Castle and put Darren and any other knight in your party. Warp back to Crownhorn Village and talk to the woman again. She will combine the three items you found into the Mordraine's Crystal.
13. Leave through the north gate of Crownhorn Village and go one screen north. Walk up just a little bit and you'll see the culprit of the warlords' invincibility: A giant, sick-looking boulder. Go into your inventory and use the Mordraine's Crystal. Boom! The boulder has been blown to kingdom come. It is now safe to approach any of the warlords in this area. They should no longer be invincible.
14. Go to the west end of this screen, then south through the Pixie Woods, and then one screen west to the rocky mountains again. This time, go north one screen. You're at the entrance of the Cape of Death. Kill the Warlords and enter. Kill the next set of warlords in the first room and exit through the back. This puts you in the castle basement.
15. Go right, then up, then take the path going left, then up, then right all the way to the end of that tunnel, then south where you see two warps. Take the righthand warp and follow the one and only passage all the way to the end until you see Phil's Shield. Get it, and then turn around and go all the way back the way you came to the warp.
16. Go north from the two warps and then go back left and take the first passage going south to another warp. Take that warp and then take the warp in the next room. If you brought Darren with you, he will fight the (well-animated) boss, Slasher. Since Darren has his shield at this point, it shouldn't be too difficult. Refer to the Dungeon Maps if you still have any trouble getting through the Cape of Death, and refer to the Boss Strategy for help with Slasher if you need it. If you did not bring Darren with you, you will fight the boss as Arthur and you will have to bring Darren back here when you are done.