+/- Dice
The rules often require you to add extra dice to a roll. These are shown in the format “+1 DICE” or “-1 DICE” (for example, shooting from elevated positions adds +1 DICE to Ranged Attacks against enemies).
+DICE
For each +DICE, add 1 dice to the Success Roll. Then roll all the dice and pick the 2 highest rolls. For example, +1 DICE means you roll 3 dice and pick the 2 highest. If +2 DICE were added, you would roll 4 dice and pick the 2 highest, and so on.
-DICE
The -DICE works in reverse, so for each -1 DICE, add 1 dice to the Success Roll and pick the 2 lowest rolls. For example, -1 DICE means you roll 3 dice and pick the 2 lowest. If -2 DICE were added, you would roll 4 dice and pick the 2 lowest, and so on.
Gameplay Example
A Success Roll is taken by a Trench Pilgrim to see if a Ranged Attack they are making with their Bolt-Action Rifle hits a Heretic model. The Heretic is in Cover, which adds -1 DICE to the Success Rolls for the Trench Pilgrim’s Ranged Attack. No other modifiers apply to the attack. 3 dice are rolled for the attack, and come up 5, 5 and 1. The two lowest rolls are picked (a 5 and the 1) giving a Success Roll of 6. The Success Roll has failed and so the Trench Pilgrim’s shot misses!
Combing +DICE and -DICe
If both +DICE and -DICE are added to the same Success Roll, remove pairs of +DICE and -DICE until only one type is remaining. For example, if two +DICE and one -DICE were added to the same Success Roll, one +DICE would cancel out the -DICE, leaving a single +DICE to modify the roll.
Injury Dice
The rules will sometimes refer to +/- INJURY DICE. These work in the same way as +/- DICE except that they add dice to an Injury Roll rather than a Success Roll.
Dice & Injury Dice
Note that if a model or piece of Battlekit has the +/- DICE Keyword, then the Keyword only applies to Success Rolls, not to Injury Rolls. By the same token, if a model or piece of Battlekit has the +/- INJURY DICE Keyword, then the Keyword only applies to Injury Rolls and not to Success Rolls.