Changes

Certain Unique monsters have Spectral Hit, which adds a random elemental property to every blow.

=When to Use Resistances=

Resistances are very important for melee, or hand-to-hand combat, characters. When fighting against monsters that have ranged elemental attacks, they can side step or dodge, but not always. Characters using melee weapons have to close in on a monster to kill it, exposing them to more elemental attacks. Resistances will reduce the amount of damage they take, allowing them to fight longer, survive otherwise impossible battles, and waste fewer Healing Potions. Some elemental attacks are difficult to avoid, such as those used by Undead Horrors, Willowisps, Unique monsters, and Bosses. In these situations, even fighters with ranged attacks may want to improve their resistances.

Your base resistance levels are determined by the game's difficulty:

The absolute minimum resistance is -100%. Resistance can never be lowered to below that value.

The Scroll of Resistance increases your base resistance level with 10 per use. Note that if you die this bonus will disappear until you join a new game. The Character Screen does not show this bug. For obvious reasons this is only a concern to Softcore Characters.

Each character has a default maximum resistance of 75%, although certain items can raise that number as high as 95%. You can never become totally immune to elemental attacks with Resistances alone.

Having negative resistances actually increases the damage players and creatures receive.