;This edition refreshes the rules, while injecting new decision-making into the mix:{{Fn|4}}

They allow players to respond to – and hopefully, thwart – the enemy’s plans, even when it’s not their turn. You can make one Reaction during each Phase of your opponent’s turn – though specific special rules can give you extra Reactions, up to a limit of three per Phase{{Fn|4}}

Legion Veterans, Terminators of all flavours, and certain Legion-specific Elites now sport two Wounds to represent their robustness in the face of withering fire. {{Fn|4}}Dreadnoughts like the Contemptor also see their profiles change to a Toughness and Wound system, as opposed to the traditional Vehicle hull system used in the previous edition.{{Fn|4}}

a key change comes from the added granularity afforded by a suffix value. Older rules such as Bulky, Very Bulky, and Extremely Bulky are now simply to Bulky (2), Bulky (3), and Bulky (5).{{Fn|4}}

*'''Deep Strike''' is changing, '''Transport Capacity''' has been tweaked, and the '''Psychic Phase''' is gone entirely.{{Fn|4}}