I was thinking about players like myself, where we prefer to build up an immensely powerful char to deal with any situation imaginable.
However that takes time and aside from an almost unnoticeable corruption hit past day 90 and lower score, there are no consequences to overplaying the game and overpreparing for any threats.
So, the idea is to increase balors' and the greater balor's levels by one for each day past 90 spent on roaming around Drakalor Chain.
It would also be lore friendly, as the increased corruption spilling from the chaos gate into the world would also strengthen the chief lieutenants of Chaos who are arguably the closest to it, both geographically and alignment-wise.

Those who close the gate before that time are unaffected and they form the majority of players, I think.
However, those few like me who like to stick around longer than that will have some serious consequences to contemplate.
Most importantly, they will have some challenge.
I hate to say it but to a heavily spoiled player like myself, the game offers *very* few challenges past mid-late game.
This RFE would partially remedy that, as I would gladly intentionally play long past the 90 day limit to have some fun on D:50 after reading a scroll of monster aggravation.
I had a char that destroyed the casino shopkeeper in 3 turns of straight melee, char that made the cat lord panic and run after two hits, char that annihilated 6 eternal guardians like they were goblins...
I understand that the game cannot keep the challenge for players that know it very well but I still think at least D:50 should scale with the player in a more reasonable way.

I had this idea after my Serpent's Bite-wielding assassin stabbed a balor to death in one go and dispatched the rest while surrounded by them without sustaining more than 100 points of damage - barely a dent in the pool of 800+ HP.
It was a powerful char, true, but nevertheless I expected a bit more from the reds.
Fistanarius is particularly disappointing in the long run - there's nothing special about him, as plenty of monsters summon minions and plenty of monsters teleport around.
An extremely experienced greater balor that hits 7 times and deals 100-200 damage with each hit, that would be something of epic proportions, assuming the player doesn't just revert to slaying ammo.
D:50 would no longer be a village dungeon to my overblown hero but something I actually have to focus on.