If the Tactical Doctrine was active for your army during the previous battle round, you can change it so that the Assault Doctrine is now active.If the Devastator Doctrine was active for your army during the previous battle round, you can change it so that the Tactical Doctrine is now active.From the second battle round onwards, at the start of the battle round, you can change which Combat Doctrine is active for your army, as follows:

During the first battle round, the Devastator Doctrine is active for your army. After pounding the foe with heavy weapons, warriors advance to lay down a hail of bolter fire before charging forth with chainswords roaring to finish the foe.If every unit from your army has the ADEPTUS ASTARTES keyword (excluding AGENT OF THE IMPERIUM and UNALIGNED units), this unit gains a bonus (see below) depending on which Combat Doctrine is active for your army. When the Adeptus Astartes fight, they employ a set of combat doctrines to eliminate the enemy. Note that all the attacks you have declared are always resolved against the target unit even if, when you come to resolve an individual attack, no models in the target unit remain in range (this can happen because of models being destroyed and removed from the battlefield as the result of resolving other attacks made by the attacking model’s unit first). If your unit is making attacks with more than one melee weapon against a unit, and those weapons have different characteristics profiles, then after you have resolved an attack with one of those weapons you must, if any other weapons with the same characteristics profile are also being used to make attacks against that unit, resolve those attacks before resolving any attacks against the target with a weapon that has a different characteristics profile.

Different attacks made with such a weapon can be made using different profiles if you wish. If the selected weapon has more than one profile that you must choose between, you must declare which profile is being used at the same time. If a model has more than one melee weapon and can make several attacks, it can split them between these weapons however you wish – declare which attacks are being made with which weapons before any attacks are resolved. If a model has more than one melee weapon, select which it will use before resolving any attacks.

Crimson fists sicaran battle tank