In the mean time, before the Deepfreeze is finished, could the music boxes for that biome be sold? I like the songs for them but there's currently no way to get the music boxes without cheating.
I take issue with the Challenger in general. The mob that drops the shards is a rare spawn even with a hugely increased spawn rate. You would have to farm this mob quite a bit to get enough shards to fight the Challenger multiple times. Then the Challenger requires quite a bit of wins to be able to buy a full armor set and weapons for one damage type. Sure fighting a boss multiple times to get all their loot is nothing new, but I find it a major pain to even get the medals. It feels very grindy. Even by mistake or design, Fargo's boss item selling NPC doesn't even sell Challenger Medals after defeating him once.
The biggest offender is the DPS cap. If you must have one, can it not punish the player? I wasn't even using Calamity weapons and I still reached the DPS cap. I was also following the Boss Checklist order and by the time the Challenger came up, I had to intentionally use a weaker weapon as not to hit the DPS cap. Actually, that didn't entirely worked. Using TheJoostMod, I used the Mutated Arm Cannons. It does a lot of damage, but if I used it when the boss charged at me, all the missiles would hit and trigger the DPS cap. So I had to make sure I didn't attack when the boss charged to avoid risking getting punished. I did have the more powerful Warhammer of Grognak, but that was too powerful for sure.
Also, how come the player suffers from a powerful debuff if you don't have a lunar sigil equipped? I don't understand that. Why be required to wear a specific accessory? A 25% damage increase for a specific damage type is powerful even by other mod post Moon Lord standards, but why make it a requirement? Why would a damage boosting accessory protect you from a powerful debuff? I didn't even know this was a feature till I read about it on the wiki and therefore made the fight a lot more manageable.