Enigmatic NPCs are NPCs that appear once in a while and disappears after being disabled for a few times. They cannot be disabled unless certain secret conditions are meet. These conditions are for players to figure out. Once it appears in your battle list, it wouldn't appear in any other of your legion mates' so it must be shared. It's combat log displays which legions has disabled it first and how many times it can be disabled before it disappears until a certain time (weekly, monthly or even yearly). The drops from these NPCs are just as enigmatic as well. You have to figure out what they're used for.

Example 1:

Enigmatic Apparition
Attacking this NPC adds to its hull instead but sometimes certain attacks damages it.

Solution: Must be attacked in a particular order (the order is different every time the NPC appears) based on race. (e.g. Konqul - Human - Sillix - Aerlen - Inergon ... with at least 4 races attacking it).

Reward:
Some kind of a crytogram that when solved - spawns an extremely rare Enigmatic NPC in your battle tab.
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So what do you think?

-1, Would take to long to figure it out before it disappears with the race, plus some races wont get it.
I like the way you put in they spawn yearly,monthly,dayly,etc... but thats it, the other need a bit of tweaking

lol
For me the more difficult, the better. There are so many things to make it hard to figure out. Ranks, artifacts, the number of members currently disabled, player's combat reputation, consecutive days of not being disabled, player's verbosity in the legion comm, player's temperament, certain words being used in the comm etc. etc. It will be frustrating for most

Frustrating is right. Puzzles are fun, but not when the puzzle demands you pull your own tooth out before you can fit the pieces together.

I like it, just dont make it ridiculously powerful and spawns only at high ranks since many low legion are badly coordinated and shoot at anything that comes by.