-% Target Defense

September 2, 2026

−% Target Defense lowers the defense of the target by a percentage of its total when the game works out whether an attack lands. It does nothing to damage, and it is not a debuff left on the monster for the rest of the party: it only applies to attacks made by the unit wearing it. Lowering defense this way is mathematically the same as raising Attack Rating, which is what makes it useful long after Attack Rating charms have stopped being worth a slot.

What the percentage is worth

The chance for an attack to land is:

100 × AR ÷ (AR + Defense) × 2 × Attacker Level ÷ (Attacker Level + Defender Level)

Target Defense multiplies the Defense term by (100 − the percentage) ÷ 100. Shrinking the bottom of that fraction and growing the top do the same thing, so the property is equivalent to multiplying Attack Rating by:

100 ÷ (100 − % Target Defense)

−% Target Defense expressed as an Attack Rating bonus
Target Defense	Attack Rating multiplier	Equivalent bonus
−20%	1.25	+25% Attack Rating
−25%	1.33	+33% Attack Rating
−33%	1.49	+49% Attack Rating
−50%	2	+100% Attack Rating
−75%	4	+300% Attack Rating

The important part is that it multiplies with +% Attack Rating instead of adding to it. A character already sitting on +200% Attack Rating from gear has its rating tripled; adding −50% Target Defense doubles that again, for a sixfold total, which is the same as running +500% Attack Rating. The same −50% is therefore worth +300% Attack Rating on that character and only +100% on one with no Attack Rating bonuses at all. It gets better the more accuracy is already stacked, not worse.

Stacking and the point of no return

Percentages from everything the attacker is carrying are added together, so a Eth Rune in each socket of a six socket weapon reaches −150%. That is the ceiling in an unmodified game: no single item goes past −50%, and only weapons carry the property at all.

Defense cannot be pushed below zero. Against a regular monster everything beyond −100% is therefore wasted, and because the reduction is halved against the tougher units, everything beyond −200% is wasted against every target in the game. In practice the halving means the realistic ceiling of −150% still only strips 75% of the defense off a super unique or an act boss.

Because the equivalent Attack Rating multiplier is 100 ÷ (100 − x), the value of each extra point climbs steeply as the total approaches −100%. Going from −25% to −50% is worth as much as the whole first −25% was; going from −50% to −75% doubles it again.

Compared with Ignore Target's Defense

The two properties look alike and behave nothing alike. Ignore Target's Defense is an on or off effect that sets defense to zero outright, but only against regular monsters, minions and pets. It does nothing to a champion, a unique, a super unique, an act boss, a player or a mercenary, which is exactly the list of targets where accuracy is hardest to come by.

Target Defense is the opposite trade. It never zeroes anything, but it works on every target, at half strength against players, mercenaries, super uniques and act bosses. Against a boss it is the only one of the two doing anything at all, and it is the reason a duelling or boss killing weapon is judged on its Target Defense rather than on Ignore Target's Defense.

They stack without interfering. Grief carries both: Ignore Target's Defense from the runeword itself and −25% Target Defense from the Eth rune inside it, so it covers regular monsters with one and everything else with the other.

Limitations

The reduction is halved against players, mercenaries, super uniques and act bosses. Supplying −100% removes only 50% of their defense.
It only applies to attacks made by the unit wearing it, Blade Shield included. It is not shared with the party and it does not linger on the monster.
When two weapons are equipped, only the value on the attacking weapon counts. That applies to Dragon Talon, Dragon Tail and Dragon Flight as well, so an assassin gets the bonus of whichever claw the game picks for the blow.
The chance to hit shown on the character screen when hovering over Attack Rating ignores it. The displayed number is lower than what the character actually achieves.
It changes only whether an attack lands. Once it does, the damage calculation is untouched.

Sources

No helm, body armor, shield, ring, amulet or charm carries it, and magic and rare items cannot roll it as an affix. Every source is a weapon: a unique, a runeword, or a socketed Eth Rune, which grants −25% on its own from required level 15. Every weapon runeword built with an Eth rune inherits that −25%, which is why so many of them appear in the list below.

Serpent Lord at required level 9 is the earliest source in the game and already carries the maximum −50%, though a Long Staff is a poor place for it. Razortine at level 12 is the first one on a weapon a melee character would actually swing.