Find the Head Kobold and sayto him "disease", then sayto him "yes". Now find the Kobold Adventurer to the north and sayto him "scroll", then sayto him "yes". Find the morkoth, kill it, give the crown to the Kobold Adventurer, and he will give you a cure disease scroll. Take the scroll back to the Head Kobold and give it to him. If he gives you a phrase but does not ask for 15,000 gold, it is the wrong phrase, so kill him and wait for repop. If he does, give him the 15,000 gold and find the fire golem to the northeast (he guards the bridge in the room Across The Writhing Runes). Sayto him the phrase and you will be transported. Search for the hidden nw (bash or magic unlock) go nw, sw, se, se (another bash/magic unlock door). Take the vial from the chest, and you will get the mark.
WARNING: The last room with the chest and mark is CPK.
For violating the hallowed grounds of the Temple of Sumter, the Powers have granted thee a Mark. You have been granted the Mark of Trespassing! You gain 235,000 experience points! You gain 41 practices!
Note: Alternatively you can get cure disease scrolls from Atlantis.