If completed, until the end of your opponent’s next turn, that unit is said to have Set Overwatch. The action is completed at the end of your turn. One or more units from your army can start to perform this action at the end of the Move Units step of your Movement phase. 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.

Leman russ battle tanks rules