try to replace this:
d.purge_area(750000,620000,817400,689400)
with another command. for me it looks like there is an kind of overflow in there ...
I think it´s because of the huge area you wanna clear. The more players are online and get in flame dungeon, the more mobs are there and the greater the array or dictionary gets where the pointers to the monsters in that area are located.
For example ( simply an example i cannot look the function from my mobiles correctly):
If in d.purge_area or an subscending function there is an array with the size of 32767 is defined as the temporary space for the monsters
and each flame dungeon has 2000 mobs at the moment.
If the dungeon is opened 10x then 2000 * 10 = 20 000 = < 32767 ---> everythng is fine
but if it´s opened 20x then 2000 * 20 = 40 000 = > 32767 ---> Memory overflow ---> Core crashes.