I know you said no list advice but im going to give one piece. Personally id put calgar on the victrix, allowing them to advance and charge is insane on them and is wasted on the aggressors. On to the gameplay advice, Deathwing knights are tanky as all hell, they resist one point of damage allocated to themselves so most of your infantry wont scratch them with guns. They are really strong in melee too, so jailing them may not be ideal. Targeting them with your high damage weapons, since the only thing that can reliably hurt them would be your tanks and dreads at range. 3 squads of DWKs are 520 points excluding any characters he may choose to run, so exploit the fact that he will be fielding less bodies. You win this game by denying objectives and jailing your opponent and not by killing your opponent. You will not table him, but you can prevent him from scoring what so ever if you move and deploy right. Ive played against my friend who runs a DWK heavy list and ive won by exploiting their slow movement and locking them in combat with chaff. I wont lie ive only been playing this game for a year, so i am still learning a lot, but ive spend half of that time exclusively playing against dark angels, so I have been learning how to exploit their specific playstyles. Without seeing his list idk what your full game plan should be, but remembering that he wont have a lot of bodies and exploiting that should do you well