Keep Exotica as it is... but give folks some other benefit in addition to the location of Exotica if they finish that mission chain.

Exotica is not able to be taken without the consent of the people who have it. Even if it wasn't the Dysonians, any legion of respectable size who owned it would be able to forever defend it.

To go through a big chain of missions to get the location of a world you can never take and never remove from your star map seems like a punishment. Why not give the location of that world, and an item that turns an existing world into a lower level Exotic?

My suggestion:
Exotica Duplicator - turns any world it is used on into an Exotic with x5 resources.

Nice idea about tangleable benefit for completing mission other than gaining location of the Exotica.. Maybe gain benefit just to find Exotica AND visit there (not needed to own) to earn something valuable in return as "thank you for visiting Exotica" such as sovenior etc. Maybe a juicy ship artifact such as shield or whatever.. or perhaps a boost to future legion starbase system or something like that..

But I like the idea of additional benefit for completing mission other than just useless location just to stare at Exotica forever..

Good idea. Once I realized how useless the mission was I stopped doing it because it really is a punishment at this point.

Like the " your ship just visit Orion " in master of orion " serie game. And here, A huge monster no way to kill Guard Orion.

At least a set of purple fuzzy dice or something.

Maybe call whatever artifact "Piece of Exotica", not sure yet what it could do, except maybe act like an ecube or something.

chunck of exotica: turns any planet used on into average 11xmegarich mining, 9xmegarich arts and 10xmearich research... you would need to make the last mission harder to do.

Essence of Exotica - +3 to all production, grants immunity to artifacts.

That would be godly ha. Put all artifacts on Dyson then use essence on it then it's golden.. That will make mission extremely attractive and rather unique.. I like the idea of it.. It might help to reduce chance of Dyson invasions that Dysonians managed to invade twice successfully..