Easy way to fix HNMs, bots cannot do everything they required certain conditions to work. Small spawn areas or spawns that where timed. Example every 20-24hrs garenteed in a small room.

Do this:

Tiamat or whatever.

Spawn conditions: 0-8days real life can spawn at any second can be 1 sec after killed or 8 full rl days(simple random # generator)
Spawn location: can take any other mobs spot in Corethas throughout the whole zone.
Drops: 1 Piece of good loot 100% of the time, with the chance of more.

While this still could technically be botted I guess with bots that say when a mob spawns, a bot claim is near impossible in this situation due to size of spawn zones. Also prevents camping unless you are just insane. too large of an area and too big on a spawn window would need a ls of 120 ppl camping the whole 8 days to find it.

Have this drop X leet item. But have it also be a drop from say crystal tower which will probably be instanced. 2 chances to get it. So no issues for those who do not like camping things.