Shields

Version 0.33: This article is up to date for the latest stable release of Dungeon Crawl Stone Soup.

For the skill, see Shields (skill). For the item formerly known as just a shield, see kite shield.

“Let who will boast their courage in the field, I find but little safety from my shield. Nature's, not honour's, law we must obey: This made me cast my useless shield away, And by a prudent flight and cunning save A life, which valour could not, from the grave. A better buckler I can soon regain; But who can get another life again?” -Archilochos. 7th cent. B.C. trans. William H. Goodwin, 1878.

Shields are a kind of armour worn on one hand, preventing the use of two-handed weapons; they make use of the Shields skill. Unlike other armour, shields increase a character's SH defense, giving you a chance at blocking physical (and some magical) attacks entirely. There are three types of shield, from smallest to largest:

• Buckler
• Kite shield
• Tower shield

Orbs also occupy your off-hand slot, but provide no shielding, instead granting assorted magical effects from their special egos.

Some magical effects can also increase your SH score.

Shield Penalties

Wearing a shield imposes penalties to attack speed, EV, and spellcasting. While the penalty for wearing a buckler is almost negligible, a tower shield can seriously slow your attacks and make spellcasting unreliable.

EV Penalty

Your shield EV penalty is equal to:

Stronger characters are less encumbered by shields, and anyone can eliminate shield penalty by maxing out the Shields skill.

Shield type	Encumbrance
Buckler	5
Kite shield	10
Tower shield	15

The EV penalty is subtracted directly from your evasion. Your unrounded EV penalty is also used to calculate the other penalties.

Attack Penalty

This penalty applies to melee attacks (including unarmed attacks), ranged weapons, and throwing weapons.

The shield penalty, in units of EV, is converted into attack delay, in units of aut. When you attack with a shield, it'll take from EV_penalty to EV_penalty + 0.05 aut longer. If the penalty is not an integer, it is rounded in a weighted manner.

Note that it is in units of aut, not decaAut or "turns". For reference, having 1 EV penalty slows you down by 1 aut = 0.1 turn.

Spell Penalty

The spellcasting penalty is significantly more complicated. Shields add to the "SpellFailure" variable, not to be confused with your actual % chance of failure:

SpellFailure = 19 * ev_penalty

For reference, the penalty from 12 SpellFailure = 1 level in every spell school (excluding Spellcasting). 15 SpellFailure = 1 level in every school, including Spellcasting.

This number is then modified by various functions described in the spell success page.

Egos

Bucklers, kite shields, and tower shields can spawn with the following egos:

• ~3%, resistance
• 10%, fire resistance
• 10%, cold resistance
• 10%, poison resistance
• 10%, positive energy
• 19%, reflection
• 39%, protection

Shields of cold and fire resistance can also occasionally be found in ice caves and volcanoes, respectively.

Every orb has its own ego; see the orb page for more details.

Blocking

As long as your SH is above 0, you can block melee and ranged "projectile" attacks. Your ability to block does not depend on EV; shield blocking is done before rolling your evasion or your AC.

When you attempt to block a valid attack, the attacker rolls a pierce value and the defender rolls a block value; if the attacker's value is lower, (see below for more details). However, there is a hard limit on the amount of attacks you can block per player turn.

Blockable attacks

What can be blocked

• Melee attacks, Ranged Weapons and non-penetrating Throwing weapons.
• Spells that fire single-target projectiles, like Iron Shot, Poison Arrow, Orb of Destruction, Sandblast...

What can't be blocked normally

• Piercing attacks: Javelins, Bolt spells, Starburst...
• Perfect accuracy/never missing attacks: Magic Dart, Smiting, Chain Lightning, Explosions (Fireball, Damnation), Shatter...
  • Orb of Destruction is the only spell that ignores EV, but can be blocked.
• Enchantments: Agony, Pain, Confuse, everything that checks willpower.

The warlock's mirror can block piercing attacks, perfect accuracy attacks that target you in a beam path and aren't AOE (e.g., Magic Dart), and enchantments. Piercing attacks use the normal SH formula, while perfect hit attacks and enchantments use a special formula.

Max Blocks

Each type of shield (or lack thereof) can only block a certain number of attacks per player turn:

Shield type	Max Blocks
None	1
Buckler	2
Kite shield	3
Tower shield	4

SH calculation

If you are wielding a physical shield, its SH is determined as follows:

• Your Base SH is determined by type of shield. 3 for bucklers, 8 for kite shields, 13 for tower shields.
• Add Skill Bonus of (base_SH/40 + 0.19) * skill.
• Add Stat Bonus of DEX * 38 * (base_SH + 13) / 5200.
• Add Enchantment value. +1 enchantment = +1 SH.
• Add 0.57 SH.

All other sources of SH (Qazlal shield, amulet of reflection...) are flat bonuses, and are added on top of the physical shield bonus. The final value is rounded to the nearest integer and displayed as the player's SH value.

If you are paralysed, petrified, or asleep, then SH is set to 0 regardless of any other factors.

Chance to block

The game compares the attacker's "pierce value" to the defender's "block value".

The attacker's pierce value is dependent on their to-hit (accuracy) and the type of attack:

• Melee attack: 1d(15 + to_hit/2)
• Ranged attack: 1d(1.3×to hit)

The defender's blocking value is equal to:

• All attacks: 2d(4×SH)/6 - 1
• Divide by 3 against melee attacks from invisible opponents.

If the blocking value is greater or equal than the attacker's pierce value, the attack is blocked.

History

• Prior to 0.31, shields did not have a hard limit on the number of attacks you could block. However, for each attack you blocked, future blocks attempts were less likely (attackers' pierce value was 1d(15 + to_hit/2 +5 × past_blocks^2) for melee, similar for ranged). Also, instead of gaining 0.82 SH by default, the first three levels gave an extra +0.19 SH/level, and you only got 0.25 SH by default.
• Prior to 0.30, species size impacted shield encumbrance and SH score. Larger species were less encumbered by shields, but received slightly less SH from kite shields. Smaller species were the opposite, more SH from bucklers/kite shields, but more encumbered by them. Strength had no effect on shield penalties.
• In 0.28, magical orbs were added as a new category of off-hand equipment.
• Prior to 0.28, shields had a different EV penalty formula, EV_penalty - skill / (5 + size_factor) (buckler = 0.8 EV, kite shield = 3, tower shield = 5). Using shields at 0 skill was more encumbering, but certain skill thresholds (regular size species: 4 skill for buckler, 15 for kite shield, 25 for tower shield) negated penalties entirely. They also had a to-hit penalty. In addition, the two larger shields used strength (along with dexterity) to determine bonus SH.
• Prior to 0.27, shields had a smaller and randomized penalty to attack delay (previously: smaller of {1d(20 * EV)/20, 1d(20 * EV)/20} rounded down).
• Prior to 0.25, kite shields were known as just "shields" and tower shields were called "large shields".
• Prior to 0.17, unarmed attacks had a speed penalty when attacking with a shield equipped.
• Prior to 0.16, the amount of skill required to negate penalties for wearing a shield was more complex.