Mortarion

If your Army Faction is DEATH GUARD, while an enemy unit is within Contagion Range of this unit, subtract 1 from the Toughness characteristic of models in that enemy unit. Contagion Range changes over the course of the battle, as shown below.

CONTAGION RANGE
1st Battle Round: Contagion Range = 3"
2nd Battle Round: Contagion Range = 6"
3rd Battle Round Onwards: Contagion Range = 9"

During the Declare Battle Formations step, select one of the Sicknesses below. Until the end of the battle, all units from your army with the Nurgle’s Gift ability gain the selected Sickness. 
- Skullsquirm Blight (Aura): While an enemy unit is within Contagion Range of this unit, worsen the Ballistic Skill and Weapon Skill characteristics of weapons equipped by models in that enemy unit by 1. 
- Rattlejoint Ague (Aura): While an enemy unit is within Contagion Range of this unit, worsen the Save characteristic of models in that enemy unit by 1. 
- Scabrous Soulrot (Aura): While an enemy unit is within Contagion Range of this unit, worsen the Leadership and Objective Control characteristics of models in that enemy unit by 1 (to a minimum of 1).’
If you control an objective marker at the end of your Command phase and a DEATH GUARD unit from your army is within range of that objective marker, that objective marker is said to be Infected and remains under your control even if you have no models within range of it, until your opponent controls it at the start or end of any turn. In addition, while an objective marker is Infected and under your control, it has the Nurgle’s Gift ability as if it were a unit from your army (so enemy units within Contagion Range of it will have their characteristics modified).

Some models have 'Deadly Demise x' listed in their abilities. When such a model is destroyed, roll one D6 before removing it from play (if such a model is a TRANSPORT, roll before any embarked models disembark). On a 6, each unit within 6" of that model suffers a number of mortal wounds denoted by 'x' (if this is a random number, roll separately for each unit within 6").

Some models have 'Feel No Pain x+' listed in their abilities. Each time a model with this ability suffers damage and so would lose a wound (including wounds lost due to mortal wounds), roll one D6: if the result is greater than or equal to the number denoted by 'x: that wound is ignored and is not lost. If a model has more than one Feel No Pain ability, you can only use one of those abilities each time that model suffers damage and so would lose a wound.

DEATH GUARD INFANTRY units from your army that are not embarked within a TRANSPORT have the Scouts 5" and Stealth abilities.

During the Declare Battle Formations step, if every model in a unit has this ability, you can set it up in Reserves instead of setting it up on the battlefield. If you do, in the Reinforcements step of one of your Movement phases you can set up this unit anywhere on the battlefield that is more than 9" horizontally away from all enemy models.

If a unit with the Deep Strike ability arrives from Strategic Reserves, the controlling player can choose for that unit to be set up either using the rules for Strategic Reserves or using the Deep Strike ability.