Need Help Getting Mind Rot Helmet And A Boss Altar Not Working In Dernel Jungle

I'm currently trying to get the items in a build I got but I need some help.
I'm missing the Mind Rot which idk how to get , and the Back-Up Plan which is supposed to be at the Boss Altar at Dernel Jungle but it doesn't work , would really appreciate if someone could help me with those 2 problems.

 

The boss altar needs Skien's Amulet or smth, you need to kill General Skien to get it. To access Genera Skien, you can find instructions here (the coords are 396 64 -3549). To get Mind Rot, you can just buy it off the market

 

Already got Skien's Badge and it doesn't do work , and there isn't any Mind Rot on the market.

 

If there isn't a Mind Rot, you can ask on the forums, and if the Badge doesn't work, try /classing, switching worlds, or getting someone else to right-click the altar (all players nearby will be teleported to the arena)

 

Its not tradeable and idk if its supposed to be like that but the text on the Boss altar is random symbols and idk if its supposed to be like that.

 

I meant, someone else can get the Badge themselves, you both go to the enchantment table, they right-click it, and you both get teleported

 

Ok but is the text on the altar supposed to look like that?

 

Yep, it's obfuscated text.

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Also, make sure you're prepared for the fight, Skien's Revenant has like 100,000-200,000 HP (I'm too lazy to do the math and add up the HP of his phases)