Location: From Morthan s 2w 4s e 2s w, and say “open durin” (in any language). Dwarves can open it anytime, other races between midnight and 3am.
Strategy: To get into knight's rooms, first find iron pick in the underwater room (3s 2e 2s 2e 2s d n from entrance), wield it and start “dig east” from the room under entrance. When you finish digging, the pick will break in your hands. Go east. In that room loads about 20 small and middle snakes - so mage with quake will rock here. First quake small snakes, let warrior go in, rescue mage and finish 4 green snakes.
Then go east, fall down, quickly stand and nuke slaves (they are very low on hps and will die pretty fast - but they parrysplit and cast). After slaves die, start killing knight: keep him bashed - he hits hard (though not as hard as willow/kraken, and has much less OB). Exit back is up from knight's room (where he pops and where you will fall from above), secret - rottenvines. Also, to go back up, you must lure him to south room cause he won't let you go up when he's in room. He tracks in those 2 rooms but he's slow.
If zone repops while you are doing SK, the hole will close too. Secret back from snakes - earthwall.
Btw, it's impossible to do SK during winter - due to frozen water (no way to get pickaxe from underwater).
Level: Hero thief; legend caster; hero buffer + hero hitter/basher or hero caster. Hero mage can do him too, though it takes much time, and also store and quake needed.
Loads: (sometimes); Engraved warhammer, thick metal plate, great helm. (usually); regular plate, full metal helmet; 3 large warhammers on slaves.
Mobs unique to the zone: