"I AM MORGAROTH, LORD OF THE TRIANGLE... AND YOU ARE LOST!"; "MY SEED IS FEAR AND MY HARVEST ARE YOUR SOULS!"; "ZATHROTH! LOOK AT THE DESTRUCTION I AM CAUSING IN YOUR NAME!"; "THE TRIANGLE OF TERROR WILL RISE!".
Don't try to go near him unless your level is high (100+ recommended). To block it a knight idealy needs around 2,500 hitpoints (at least level 185+) and as many stone skin amulets and might rings as possible. Preferably, have at least 15 shooters or more. Shooters should all wait in the same square upstairs while the knight lures Morgaroth to the left or right side of the stairs (to avoid demons from the south). Then, all shooters should go down in the same square (to be able to go up fast in case of retarget) while mages shoot Icicles or Avalanches, paladins preferably shoot Shiver Arrows and Holy Missile Runes (only if you have a bow with a range of 6+ sqms).
The Knight will need constantly heal, at least 3 to 6 Druids casting straight Exura Sio, and sorcerers can help healing with Ultimate Healing Runes. Druids can use Wild Growth runes and other vocations Magic Walls around the Knight to make Morgaroth stay diagonal and to keep away summoned Demons. This is a dangerous technique if Morgaroth retarget shooters, the knight can get surrounded by non-summoned demons, making him unreachable to Morgaroth, consequently Morgaroth will keep attacking shooters.
On Optional PvP worlds, a group of players may try to help Morgaroth kill the knight blocking by making a line of magic walls between the blocker and shooters, so that the blocker cannot be healed by the druids and ends up dying. There is one simple way to avoid this, by having a few high level players stand guard for magic walls and running into them (while not taking part with the war mode), which would cause the magic walls to disappear. This can also work for removing the magic walls around the knight blocking. Provided that the player removing the magic walls are not in war mode and being shot at by others in same war.
Another strategy is that a second group of 1 or 2 knights go south from the stairs and protect the shooters while they heal the blocker from a different position.