Mercenaries and Summons do 25% damage to Act Bosses.

Character resistances take a 100% penalty.Most Superuniques gain a second random modifier to add to their preset properties.Random Boss monsters gain a third random Monster Modifiers.Further increased monster levels and stats (hit points, defense, damage, and more).Monsters that can cast skills gain 7 levels to their magical attacks.Unique and Champion Monsters gain a 66% damage bonus.Dying takes 10% EXP from the current amount needed to level up (Characters will never drop a Level).Bosses and Champion monsters have a 40% chance to drop exceptional items, and a 40% chance to drop Elite items.Normal monsters have a 30% chance to drop Exceptional items, and a 20% chance to drop Elite items.Some levels have a larger exploration area.Static Field will not reduce a monster's hit points to less than 33%.

Effects of using Freezing, Life/Mana Stealing, and Chilling Curses are halved.

Diablo 2: Resurrected Mercenaries and Summons do 35% damage to Act Bosses.

Characters suffer a 40% resistance penalty.

Most Superuniques gain one random modifier to add to their preset properties.

Random Boss monsters gain a second random Monster Modifier.

Increased monster elemental resistances.

Increased monster levels and stats (hit points, defense, damage, and more).

Monsters that can cast skills gain 3 levels to their magical attacks.

Unique and Champion Monsters gain a 75% damage bonus.

Dying takes 5% EXP from the current amount needed to level up (Characters will never drop a Level).

Increased chance of finding Exceptional items (10% from regular monsters, 20% from Bosses and Champions).Here are all the major differences in Nightmare and Hell difficulty in Diablo 2: Nightmare Difficulty Differences in Diablo 2 Completing Normal, Nightmare, and Hell is considered 'beating' Diablo 2, but getting a character to max Level or finding a perfect build (like the amazing Lightning Sorceress build in Diablo 2 Resurrected) are additional challenges players can try.

Diablo 2 prayer skill