Trial and Trerror. the campaign is one huge dungeon filled with ridiculously hard epic fights…There was this crazy gnome lich whith way over 30 HD who could cast quickened breach + bigby’s + missile storms all day. The Epic Campaign offers a similar feel difficulty wise. When 5+ Epic warlocks concentrate their blasts at one char, it’s over.
In The last of the Danaan mod there’s alot of realistic and tactical combat, you HAVE to use positioning, stelth, traps, potions and whatever spells you got in the best way possible. My Ranger/Druid used to turn into a pin cushion for arrows a bit too often.
Also if you’ re using reeron’s spell fixes, every fight with greater invisible opponents is a nightmare if you don’t have a way of dispelling. Enemies with assassin levels = pissing in pants.
End of Legends in the Kingdom of Algard had countless encounters with respawing outsiders. Very tough but not in a creative way. Also controlling a 9 person party is a pain.
The OC and even MOTB are too easy, they practically require no tactical thinking at all. The OC can be won by Khelgar, Qara and Neeska alone while in motb you are so powerful and overequipped that it just isn’t funny. Some fights can feel moderately hard, like the 600hp gnolls in thay or the vampire monks if you haven’t the right spells.