I’ve been trying to think of a perfect ‘late gamer content’ that could be succesful in E&P world, both rewarding the long-term bored players looking for just any challenge (hi) but at the same time not leave the intermediate+ players feel excluded and ripped off rewards.
The game which handled the end game content perfectly for me is Diablo III + Reaper of Souls, and their Nephalem Rift (and Greater Rift) concept. Once you finish the storyline, you get access to this new portal where after farming certain set of items from various game bosses, you can try your chances to fight in time-limited battle against certain amount of mobs and bosses, with a neat mechanic of constantly increasing difficulty the more difficult stages you beat within the time limit. Of course, the higher you are the better the rewards, but if you overestimate yourself and not finish in time, the rewards are cut. Similar concept to E&P titans, although with cap set far higher, so high that even best equipment won’t be enough to finish the highest levels… but if you are determined and push your luck, you may keep trying for bragging rights. More about it here - Nephalem Rift | Diablo Wiki | Fandom (I hope you do not consider an old PC game a competitor and won’t flag this, I just think it visualizes the idea well)
I think it wouldn’t be that difficult to introduce something of similar concept in E&P. Of course, rename it to avoid lawsuits from Blizzard 
This would be an alternative game mode, accessible after collecting certain set of farmable items dropping from various bosses (maybe on difficult levels of S2/S3 but not obtainable with tickets), where you would enter a PVM game and your job was to:
- kill as many of them as possible, with each coming wave being stronger / bigger in numbers
- deal with any randomly spawned bosses, maybe even some heroes serving as bosses or assisting the regular monsters on some stages
- kill ‘little titans’ like what we had with the Ursena fight at the end of S2
- whatever else!
Now either set a time limit to kill all (could grow with difficulty) or just leave it for the difficulty to balance it out.
How to make it more interesting:
- rare spawn mobs/chests which would drop some of the rarer game’s specialties (of course the higher you are the better the chances of meeting them) - Diablo had a neat concept of Goblins, that were rare to find and even when met - difficult to beat the hell out of them because little rats were moving at speed of light; could be something similar here - chest/rare mob must be taken down in particular turn or it just disappears/devalues/spits an ugly effect your way slowing you down
- randomly applying certain ‘special rules’ we know from the seasonal events, Atlantis levels, Valhalla events, weekly tournaments color restrictions etc. Yea, it may feel a bit chaotic at first, but since this would be accessible to players who have seen it all already, I don’t think that’s an issue. Only players would need to know what rule they are about to enter before selecting their rosters… This is where RNG actually helps making things interesting.
- roster wise, it opens a lot of additional possibilities… randomly not allowing certain class or color is easy way to go, but could also allow to select not 5 but 10 heroes and you’d be allowed to swap between them (eg. when they die or when you prepare for a ‘small titan’ fight). Hardcore solution: separate rifts for max 3, max 4 and max 5 star heroes, with different requirements, costs and rewards
- extra bonus for greedy developers there’s a way to boost your Rift attempt with gold / gems to have a shot at a bit better rewards at the end. But don’t make free attempts completely irrelevant (like free PoV vs pass PoV). Add maybe an extra roll for ascension mat and make other ‘paid’ rewards something cosmetic, like further customization of your profile, or an extra background when someone is raiding against you, or an avatar, or banner. There’s already too much p2w recently. If you want to make money out of it, allow an option to enter the “rift” for gems if someone doesn’t want to farm ‘keys’ from bosses, or gem cost to skip the cooldown.
- daily/weekly/seasonal leaderboards of who beat the highest level and in what time. Just for bragging rights.
To make it work, a balancing formula to the difficulty could be a nightmare to craft. But I think one time effort with perhaps some polishing to keep it interesting afterwards for increasing lifespan is worth it.
It would need balance on the ‘accessibility’ as well. It can’t be a once in a month or even once in a week event. But I can appreciate we shouldn’t be allowed to farm it all day long (because then the % for good rewards would need to be close to zero). Maybe the higher the level the more WE they cost, and similar to skipping chest waiting time, there would be a limit to how often you can visit the ‘rift’. But at least once a day would be a must if it was a ‘late gamer ultimate challenge’ oriented feature. Alternatively, create a separate flag for it so it is not WE dependent.
Now in Diablo you are allowed to take friends with you to beat the hell out of the rift. How awesome would that be but how extremely difficult to implement here. Not to derail this idea - but I also made a topic about something similar in the past… probably not everything aged well, but it’s not about the details anyway, just about the idea.
[if there are any Diablo 3 players that think Nephalem Rift was in fact terrible concept, I mean not to argue with you! I found it interesting being pretty casual player there and never thinking of climbing the ladder, just couple months of play, so I only use it as a reference to an existing concept of difficulty grinding].
