Defense

Defense is a player statistic that determines how much damage can be taken per hit. The damage the player takes is reduced by half of their defense value, altogether. Defense can be increased by equipping armor and accessories, or temporarily boosted by various buffs. No attack can be reduced below 1 damage (with the exception of a player with an ally wearing the Paladin's Shield).

Some forms of damage are impossible to reduce through defense. Damage from health-draining debuffs like Cursed Inferno or drowning in water are not reduced by defense. Damage taken from lava, however, can be reduced through defense.

Mechanics
Defense gives a flat reduction in damage, i.e. damage is reduced by a fixed amount per hit (as opposed to a multiplicative damage reduction, which would reduce damage by a percentage).

Normal mode formula
The formula is:

$$net\ damage = attack\ damage - (defense * 0.5)$$

For example:
 * With 20 defense, a 40 damage attack is reduced by 10, resulting in 30 damage taken: $$40 - (20 * 0.5) = 30$$
 * With 30 defense, a 40 damage attack is reduced by 15, resulting in 25 damage taken: $$40 - (30 * 0.5) = 25$$

Expert mode formula
In expert mode, the formula is:

$$net\ damage = attack\ damage - (defense * 0.75)$$

For example:
 * With 20 defense, a 40 damage attack is reduced by 15, resulting in 25 damage taken: $$40 - (20 * 0.75) = 25$$
 * With 30 defense, a 40 damage attack is reduced by 23, resulting in 17 damage taken: $$40 - (30 * 0.75) = 17$$

Note that in Expert mode only the player's defense follows the formula. Enemies will still take the same amount of damage as in normal mode.

Enemies
Enemies have a defense statistic just like players do, but they do not gain more protection from defense in. Enemies will always reduce incoming damage by 50% of their defense regardless of difficulty.

$$net\ damage = attack\ damage - (defense * 0.5)$$

Examples:

Armor and Accessories
A player's defense score can be increased by equipping armor and accessories. Armor usually consists of three items, granting an additional bonus, the Set Bonus, which may increase the defense score further, if all three pieces match. Some accessories grant direct defense boosts (see the following table), but all accessories can also be reforged to a maximum of +4 defense per accessory.

See armor for detailed defense information about every piece of armor.

The following accessories increase the player's defense:

Buffs and Debuffs
Buffs and debuffs can temporarily alter a player's or an enemy's defense. Currently, there is no buff increasing enemies' defense. A player's defense cannot be reduced to fall below 0.

Damage reduction boosts
All damage reduction boosts (except Paladin's Shield) affect damage taken after defense.

Armor Penetration
Armor penetration is a statistic that reduces the defense of the player's targets. For instance, a Pixie normally has defense. If the player has 5 Armor penetration, then the Pixie will be taken to have defense instead.

Defense
The highest possible defense is 165 normally, and 173 in, using the following setup: 79 + 48 + 18 + 20 = 165 (normal) and 79 + 56 + 18 + 20 = 173 (expert)
 * Armor – 79 defense in total
 * Chlorophyte Mask – 25 defense
 * Solar Flare Breastplate – 34 defense
 * Solar Flare Leggings or Vortex Leggings – 20 defense
 * Accessories (at night) – 48 / defense in total
 * Flesh Knuckles – 7 defense
 * Celestial Shell – 7 defense
 * Paladin's Shield – 6 defense
 * Two out of Ankh Shield, Moon Stone, Celestial Stone – 8 /  defense
 * Warding modifiers on all accessories – 20 / defense
 * Buffs – 18 defense in total
 * Ironskin – 8 defense
 * Well Fed – 2 defense
 * Dryad's Blessing – 8 defense
 * Guarding with the Brand of the Inferno – 20 defense

Damage reduction
The highest damage reduction possible is 73%, using the following setup: (1 - 0.45) * (1 - (0.25 + 0.17 + 0.1) ) = 0.264 = 26.4% damage taken = 73.6% damage reduction
 * Armor (multiplicative)
 * Beetle armor with shell – 45% reduction
 * Accessories and Potions (additive)
 * Frozen Turtle Shell – 25% reduction
 * Worm Scarf – 17% reduction
 * Endurance Potion – 10% reduction
 * This does not include the Paladin's Shield buff, since its damage reduction occurs before defense, and all others occur after defense.

Trivia

 * Although not possible in-game, if a piece of armor were to gain a modifier, it would apply the effects just like an accessory would. For example, a set of Warding modified armor would add 12 defense total; each piece adds 4 defense to the total.
 * If the player somehow has negative defense, they will constantly take 1 damage, and die with the death message " couldn't put out the fire".

Abwehr Défense 防御力