Casualties

During invasion, both the attacker and the defender will lose units, except for units which are immortal. These lost units are referred to as casualties.

Offensive Casualties

When attacking, the invader loses a base rate of 8.5% of the units required to break the target.

If you send 6,000 units but only 5,000 were necessary to break the target, you suffer 8.5% losses of the 5,000 units.

You would lose

$5000 * 8.5 % = 425 u n i t s$

and not

$6000 * 8.5 % = 510 u n i t s$

If you fail to break your target, you will suffer 8.5% casualties of the units sent on attack.

Attacking a wonder will always cause 3.5% casualties except for Gnome Suicide Squads.

Defensive Casualties

Defensive losses start at a base rate given by,

$3.6 % * \frac{D e f e n d e r A c r e s}{A t t a c k e r A c r e s}$

meaning that you take less casualties if you are invaded by someone at the very top of your range. The upper range of this is capped at the baseline 4.05%; you will not take increased defensive losses if you are invaded by someone smaller than you are.

This can also be increased if the attacker sends more units than required to break the target. Casualties increase or decrease linearly: sending 110% of what is needed to break will cause 110% of the expected casualties as per

$3.6 % * \frac{D e f e n d e r A c r e s}{A t t a c k e r A c r e s} * \frac{A t t a c k e r O P}{D e f e n d e r D P}$

At most, defensive casualties can be 4.8% by oversending or due to any other factors such as wonders or spells (equivalent to oversending by 133%). Conversely, a bounce will reduce casualties linearly with the amount of OP sent.

A dominion which has been invaded recently also suffers reduced casualties.

First invasion: 100% (of the base)
Second invasion: 75%
Third invasion: 50%
Fourth invasion and more: 25%

Note: This invasion modifier is only applied if it is a greater reduction (and never applied as an additional reduction) than the other reductions already in effect (such as unit-based defensive losses and the land ratio modifier).

A dominion retains its 'invaded' status for 24 ticks beginning the tick the invasion occurs. For example, you are hit once at 15:40 you will retain a recently invaded count of 1 until 15:00 on the following day.

Defensive casualties on a raze (unsuccessful attack) scale from no casualties below 80% linearly to full casualties at a failed invasion just below the offense needed to successfully invade the target.

Bounces failing by more than 20% produce zero defensive casualties.

Casualty Reduction

Casualty reduction bonuses are split into two types: unit bonuses and non-unit bonuses.

As the names suggest, the unit bonuses are inherent to the units themselves, e.g. Human Knights, Vampire Kindred, or the various Reduced Combat Loss bonuses like Dwarf Clerics. Non-unit bonuses consist of all other bonuses including techs, racial spells, and buildings.

Bonuses that fall within the same category are additive with each other. A Human with -25% casualties from techs and -25% casualties from Shrines would have only half casualties on Cavalry because both bonuses are non-unit modifiers. However, cross-category bonuses are multiplicative. That same Human's Knights, if sent on an attack, would have total casualties of

$0.085 * 0.5 * 0.75 = 0.031875 = 3.1875 %$

Non-unit bonuses cap at -80%; having max 16% Shrines (-80% casualties) and -25% casualties in techs means you have 5% Shrines that are above the cap and cannot apply their bonus.

Casualty reductions do not work with Gnome Suicide Squads.

List of Casualty Reducing Bonuses

Type	Unit	Non-Unit
Offensive Only	Firewalker Salamander: 50% fewer casualties on offense Halfling Staff Master: 40% fewer casualties on offense Spirit Ghost: 30% fewer casualties on offense Spirit Spectre: 80% fewer casualties on offense in range
Defensive Only	Lycanthrope Werewolf: 50% fewer casualties on defense Spirit Banshee: 50% fewer casualties on defense Goblin Shaman: 50% fewer casualties on defense Icekin Snow Witch: 50% fewer casualties on defense Orc Voodoo Mage: 50% fewer casualties on defense	None
Offensive & Defensive	Dark Elf Spellblade: 15% fewer casualties Human Knight: 25% fewer casualties Nomad Blademaster: 25% fewer casualties Sylvan Centaur: 25% fewer casualties Vampire Kindred: 50% fewer casualties Dwarf Cleric: Reduces combat losses	Healer Hero: Variable reduction based on Hero level Battle Tactics tech: 5% fewer casualties Survivalist Mentality tech: 5% fewer casualties Battle Commanders tech: 7.5% fewer casualties Field Surgery tech: 7.5% fewer casualties Ruby Monolith Wonder: 10% fewer casualties Regeneration spell (Troll only): 30% fewer casualties Bloodrage spell (Orc only): 10% increased offensive casualties

Reduced Combat Losses

Units with reduced combat losses, or RCL, offer a range of casualty reduction from 0 to 50% based on what percentage of your army consists of the unit. Your army consists only of trained units in this calculation: draftees do not count.

$R C L r e d u c t i o n = \frac{R C L u n i t / T o t a l U n i t s}{2}$

If a dwarf sends 10,000 Clerics on an attack and no additional units, their offensive casualty reduction will be

$R C L r e d u c t i o n = \frac{10, 000 / 10, 000}{2} = 0.5 = 50 % r e d u c t i o n$

If that same dwarf leaves 10,000 Clerics at home along with 10,000 miners their defensive casualty reduction will only be half of their offensive reduction,

$R C L r e d u c t i o n = \frac{10, 000 / 20, 000}{2} = 0.25 = 25 % r e d u c t i o n$

Immortality (Almost Never Dies)

Some units have a special ability which renders them immortal. The term almost never dies is used in the Scribes.

These units suffer no casualties at all except for certain circumstances.

Immortal units always die at the base rate of 3.5% when attacking Wonders.
An overwhelmed bounce is a failed invasion by 20% or more in OP vs DP.
Vampire Bloodreavers are immortal unless Feast of Blood is active.
Undead Abominations are immortal when paired with at least 1 Necromancer.
Firewalker Phoenix are not immortal, but are reborn 6 hours after death/invasion and show as returning troops.