So you're end game, you're bored, and you've gotten pretty good at this game. You've got great gear, good knowledge, and skillful play ability.
You're looking for a challenge.

Here's the idea - we introduce three things that help make the game challenging to those who find it much easier. These three things are: challenge depths, daily challenges, and challenge trinkets.

CHALLENGE DEPTHS
A "challenge depth" would be a depth in which all players are given a debuff. Up to 3 debuffs can be applied, and are applied randomly to each player. In challenge depths, upon completing a level, the crowns and heat earned from the level is multiplied by 10%-30% for crowns, and 15%-45% for heat, depending on how many debuffs are applied.

When a player dies, a debuff is removed from them and their end level bonus is reduced by 10% for crowns and 15% for heat. If a player goes down 3 times in a string of challenge depths, they simply are playing these depths as normal, and aren't getting the boosted rewards. Dying any additional times would not decrease crown or heat drops.

Challenge depths would be accessible to all players with 10k prestige, and the numbers of debuffs and thus crown/heat increases they get would increase once they reach 15k and 25k prestige.

To access a challenge depth, a player with appropriate prestige rank must activate the inactive elevator at a clockworks terminal in the arcade. Challenge depths would randomize between all level sets per depth, and would simply display the question mark on the elevator terminal.

DAILY CHALLENGES
A "daily challenge" would be a special type of challenge available to all players who have reached 5k prestige.

A daily challenge would act like a challenge depth, however it will have a set in stone debuff and level to complete. Daily challenges are unique to each player, and would work in a specific way:

1. A random loadout is generated from the player's arsenal. Gear must be of the same star level.
2. Strata is determined by star level.
3. A random arcade gate and depth lineup is selected in the appropriate strata
4. One to three random debuffs are applied to the player
5. A specific goal is given to the player from a list of challenges

Challenge goals can range from something like "deal 10 finishing blows with X weapon" to something extreme like "complete this challenge without taking damage".

Upon completing your daily challenge, you would continue one depth deeper and get an ensured treasure vault. All loot in this area would be increased by 33%, and an arsenal station would be present for you to change your gear if you want to heat something.

After completing 1-3 daily challenges within a single day, then the daily challenges will start taking levels of your appropriate rank (i.e., things you can see on the party finder) and adding them to the daily challenge rotation.

If another player joins a daily challenge player while they are actively in their daily challenge, they will be able to view the player's daily challenge as an objective (think: rank mission objective notification) and can see what player debuffs were applied to the player. They can then attempt to assist to player in their challenge to get the free treasure vault, however they won't get the 33% increase of loot.
Once a daily challenge player has reached the "goal" floor for their daily challenge, their party becomes locked. This is to prevent inviting players for an ensured treasure vault. However, it doesn't stop players from inviting friends to help them on the final floor so they can complete their challenge.

All daily challenges would have the same party restrictions as the levels they go into. Kicking a player, or getting to depth 25 in a Dreams and Nightmares daily challenge would prevent players from joining your party.

All daily challenges would award 30 prestige upon reaching the bonus treasure vault.

CHALLENGE TRINKETS
Challenge trinkets would act like a special kind of trinket that allows the player to apply a debuff to themself to increase crown and heat pickups. The difference here is that the player can select a debuff, however this debuff sets a new maximum value for certain bonuses. For example, a health debuff would decrease your health, but also decrease the efficiency of a health trinket if you pair it with that as well as vitapods you pick up. If you use a -2 sword damage challenge trinket, then even with black kat + barbarous thorn shield you could only get a very high damage bonus with swords.

For each type of debuff you apply to yourself, you get a 7.5% increase of crowns, and a 11.25% increase to heat, however if you are not directly affected by your challenge trinket, then it will not reward you (i.e., a challenge trinket that affects swords will not give you additional crowns and heat if you do not have a sword equipped). This reward is applied at the elevator, so you must complete levels with your trinkets equipped to get their benefit.

In the case of lockdown, challenge trinkets would increase health drops from players, grant players longer mercy frames (1 trinket grants half a second longer, 2 trinkets grants 1.5 seconds longer), and ensure sonic mode is applied. If players complete the entire match with a challenge trinket equipped, they will receive an additional 25% of their leaderboards score per trinket, and their new leaderboard score will be given to them additionally as crowns.

TL;DR - give us randomized arcade levels, missions, and trinkets that debuff the players but reward us with more crowns and heat, and in the case of trinkets, give a better fighting chance since you're sacrificing your trinket slots and debuffing yourself. Have arcade and missions be unlocked at specific prestige levels to ensure that players are ready for it.