I'm not a party player, but I feel there is a strat when you farm the whole maze except last 2 rooms (they are being farmed by a carry player). 6, 7 and 9 are treasure maps which you receive after killing a maze boss 20 times + you have all his scrolls as top grade. 6 - cockroach, 7 - scorpion, 9 - maze puppet.

I play solo and I'm able to get the treasure map 10 on the top of 679, but it's only n10 so far.
treasure map 8 you can receive during quest n23 by talking to little sister (looks same as quest n2)

to make this strat work and play in party at this role - you need to have a proper set of cards and EQP with "Ancient" prefix maxed out. The point of strat is probably to give carry player top grades and red scrolls, so he could receive the treasure maps much faster, but I'm not sure about this one.

where do you find treasure 10