I don't know who here has played TemTem but their endgame dungeons was actually a really well implemented system. For those who are unaware you paid gold to enter and then were given a few Tem to pick 1 from to start the run with up to 3 other players. As you advance through the path you'd encounter either items, dungeon currency (split between the party) or battles with Tems. If you battled the Tem you could swap your current one with the new one or continue with a battle weaken monster. There was a shop tile as well that you could use to buy items or heal your Tem but if someone used all the currency before you got there as well you we're just kinda out of luck so it required some team work to make sure everyone could get to the end. If you fainted during the dungeon you could buy yourself back using a big chunk of the teams currency which most times lead to getting to the end and noone being able to enter so it became common that all parties ran under the rule of if you died you just had to go re-que. The end reward was the Legendary Tem that was only obtainable once a week and a bunch of items ranging from potions to items to fix IVs and EVs, so you didn't need to get the perfect tem you could eventually acquire enough of the items needed to make it perfect. To give the mode replayability after your first weekly completion the items you got from beating the dungeon run was normally equal or more than the cost of entry to make it worth investing your money into the mode.
The mode had it flaws but for a monster catching end game PvE content it was actually pretty fun to do with your friends and even with randoms as long as everyone sorta knew what they were doing and/or weren't trolling by using all the currency or buying themselves back after a wipe. Hopefully when we get dungeons here as well, its implemented in a way that has the economy in mind but also gives it replayability as some true endgame PvE content.