Hell (difficulty)

Hell is the highest difficulty level, following in the Diablo series. Although you will have the creatures with the same appearance and the same quests as in and Nightmare, they will be much harder and deal much more damage to the player.

Diablo/Hellfire
Much like Nightmare, Hell Difficulty is present in Diablo's Multiplayer, as well as all of Hellfire. Both have varying changes, but a list below compiles changes seen in both cases:
 * Monsters will deal even higher damage per hit, and their life capacity is increased by at least x4.
 * Players will need +120% to-hit and +120 Armor Class to dish out/avoid damage like they do in Normal
 * Monsters have grown hardier to the effects of spells, resulting in a greater number of monsters possessing resists and/or immunities. For example, a Devil Kin, who resists nothing in Normal/Nightmare, now resists Fire effects.

Diablo Only

 * While the fact remains that monsters have their life capacity increased by x4 compared to Normal, tests have shown that they receive an additional +3 life to their totals after the multiplication occurs.

Hellfire Only

 * In addition to the x4 Difficulty modifier to their base/maximum life, monsters also possess a +100 bonus after the multiplication, resulting in mobs with at least 100 life even in the Cathedral section.

Warnings

 * Do not think your character can shrug off most melee hits in the later levels of Diablo/Hellfire, even with affixes that reduce damage taken. The damage dealt will stun you, no matter your level or class. You are better off avoiding most attacks rather than reducing the damage dealt per blow. This is more apparent in regular Diablo, because there are no classes that possess a stun threshold higher than 1 point per level, and because of no Reflect.
 * Casters should be aware that their spell plans will need to be adjusted for Hell Difficulty. There are even monsters immune to all elements of spell damage, resulting in a greater dependence on Golems and Stone Curse.

Diablo II/Lord of Destruction
The complete list of the effects of Hell include:
 * Further increased monster levels and stats.
 * Nearly all monsters have at least one Immunity and additional resistances.
 * Player and Hireling resistances are reduced by an additional 60, for a total of -100 in the expansion. Regular Diablo II players only suffer -50% all resists, but have less means to combat this- no charms, runes, jewels, and no Scrolls of Resistance.
 * Death results in a loss of 10% of the experience required to reach the next level. Retrieving your corpse restores 75% of the lost experience.
 * Hirelings and Summons deal 25% damage to Act bosses.
 * Duration of Freezing and Chilling effects and AI-affecting curses are reduced by 3/4.
 * Life and Mana Leech effects are reduced by 2/3.
 * Static Field cannot reduce a monster's health below 50%.
 * Many area maps are increased in size.
 * Act V has additional "Guest Monsters" from other acts to increase the difficulty.

For having access to the Hell difficulty the following requirements must be met:
 * If you are playing an expansion character, you must have defeated Baal at Nightmare difficulty.
 * If you are playing a non-expansion character, you must have defeated Diablo at Nightmare difficulty.

Hell difficulty is the only difficulty level in which the two Battle.net only quests, the Pandemonium Event and the Uber Diablo Quest can be obtained.

If a character accomplished the last Quest Act IV (killing Diablo) in non-expansion you will gain a new title.
 * Hardcore: Male will be King and female Queen
 * Softcore: Male will be Baron and female Baroness

If it is an expansion character, you must kill Baal in Act V to gain a new title.
 * Hardcore: Male and female will be Guardian
 * Softcore: Male will be Patriarch and female Matriarch