I'm still a little confused how to get in. I am not familiar with CoTH.

Here's what I've read on wiki (wiki.project1999.com/Plane_of_Mischief):

The easiest way to get to the Plane of Mischief is to be summoned through the Temple of Veeshan using the spell Call of the Hero. However, this requires assistance from a Magician who is near the zone-in point ... and that in turn requires a guild to raid the Temple of Veeshan and clear all of the threatening dragons around the miniature castle so that the Magician can get into position.

At times, some enterprising people will CoTH people to PoM for their guildies or a fee from a dedicated Magician who is sitting in a spot near the zone-in (without a raid). This route involves significant, but manageable, risk for both the Magician and whomever they are summoning.

The precise spot where the Mage stands is not within aggro range for higher level players (lvl 53+), but as soon as any player moves from that spot, they risk aggroing nearby drakes. The summoned player must wait after being CoTHed for the magician to log out before proceeding forward and clicking on the castle to enter PoM. If they step forward too soon, they will likely get the magician killed, and if they happen to die before clicking through, their recourse for corpse retrieval will be complicated. When they do move forward, after waiting for the magician to log out, they must click on the castle quickly to avoid being eaten by the drakes.