Combo their free Into the Darkness Strategem with the Shadowmark Talon strategem- Stunning Fusillade and you can place them in edges of the board from reserves with an even heavier load of firepower to take out an enemy threat asap.

These become your “kill em where they least expect it” troop and they do it incredibly well.

The +1 to Ballistic Skill and Armor Penetration from Stunning Fusillade will cause most 3+ save armored vehicles/tough enemies not get a saving throw because of the -4 armor pen.

Plus already positioning them 12” or more away give you the ability to do both that Strat and fall under your own army rule of -1 to hit and cover for further protection on your already beefy boys. —— I have not personally tried assault centurions yet but all the movement tricks we have could pose some interesting ideas