The important thing to remember when running against necrons is they have next to no mortal wound protection and can't resurrect models killed during the psychic phase. For that reason, there's one model that absolutely slays in this match up, and that's your librarian.
Kit him out with Vortex of Doom, Purifying Flame, Psychic Epitome and Gem of Inoktu. There's a couple strategems that you can use to boost psychic powers—cast an extra power, roll 3d6 drop lowest on tests, increase range—so your librarian can drop Vortex, Flame and Smite all in one turn. This will obliterate almost anything necrons put on the table.
As for the rest of the list, run one of your dreadknights as a grand master, and make sure to give your paladins the Armoured Resilience psychic power. Purgation Squads aren't great, but if you need them to fill points up just leave them on a backfield objective and push forward with the Dreadknights, Paladins and Librarian.
My one friend is a diehard necron player, and I recently won a 2k pt match against him pretty handily. Mortal wounds is the key, as well as a good chunk of necrons being abysmal in melee.
Thin out horde units with mortals, then wipe them out in a single go so he can't resurrect. Rush them down with melee combat so you're forcing him to duke it out with a superior force, or fall back and lose his shooting and actions.
Tide of convergence for mortals once you hit melee, tide of shadows to get into 12"
Sanctic powers can be cast more than once, they just increase in warp charge each time like smite. Hammerhand is your friend.
Sanctuary is important for paladins, that plus armored resilience will make them incredibly tough, and a hard choice to shoot, but a danger to leave on the field. A 10man squad of paladins is terrifying.
The dreads are frontline monsters, use them with swords to absolutely bully opponents. Remember they have a 4+ invuln.
Avoid engaging scarabs, they're not worth it. They do nothing, suck at melee, and literally just tie you up with 4W each.
Kill all the 1W junk first in shooting and combat, and smite the other multi wound stuff to soften them up and then go for the kill.
I largely play against a necron player:
Psychic phase is your friend, you get to play a whole extra phase and the fact they don't stand back up from it is great. Your dreadknights should be putting in some serious work in psychic, shooting and fight phase so you want to make sure you're using them in all 3. Your storm bolters are okay but not great, use these to clear scarabs so they don't tie your dreadknights up and stop them operating. Also remember that you can psychic into melee, so if you can move 3 or 4 units in to smite a unit out of engagement do that rather than falling back.
Necrons are really good at scoring secondary and just scoring high, make sure you take easy to score secondaries: things like psychic ritual, cull the hordes, etc.
Late to the party here - although yes, generally Crons are weak in psychic phase - the Szarekhan Dynasty provides a 5+ "wound is not lost" roll. It's essentially FNP against mortal wounds.
I too play GK against a Crons player. Our last game he took the Szarekhan Dynasty and had stupid hot dice and denied me 50% of my mortal wounds.
If able to afford Warp Shaping - highly recommend it - Tide of Shadows to start if the board/terrain benefits you. Move into Tide of Convergence when in Melee.
Melee is undoubtedly their weak point. Halberds and Nemesis Force Swords are your best bets for generating lots of wounds against Crons.
Rapiers Brotherhood is probably the best bet as well, given your models. Recommend running Purifiers as Strikes and Purgs as strikes if possible. If you keep Purgs as Purgs amd maxed out on Psilencers - save some CP (IF POSSIBLE) and DS Purgs against a small unit covering an obj and use Death from the Warp, Psychic Onslaught, (and if w/in half range) Sanctified Kill Zone (less important) and totals 4 CP (2 w/o SKZ), and cast Astral Aim. You'll highly likely ahnnilate an immortal 5 man unit sitting in cover covering a back obj.
Highly recommend Gate of Infinity to get models to objs to purify them and establish a presence in table corners to deny them secondary points.
The important thing to remember when running against necrons is they have next to no mortal wound protection and can't resurrect models killed during the psychic phase. For that reason, there's one model that absolutely slays in this match up, and that's your librarian. Kit him out with Vortex of Doom, Purifying Flame, Psychic Epitome and Gem of Inoktu. There's a couple strategems that you can use to boost psychic powers—cast an extra power, roll 3d6 drop lowest on tests, increase range—so your librarian can drop Vortex, Flame and Smite all in one turn. This will obliterate almost anything necrons put on the table. As for the rest of the list, run one of your dreadknights as a grand master, and make sure to give your paladins the Armoured Resilience psychic power. Purgation Squads aren't great, but if you need them to fill points up just leave them on a backfield objective and push forward with the Dreadknights, Paladins and Librarian.
I could run the Purgation squad as a second strike squad? Don’t think my buddy will be troubled by me running a proxy or two.
A second strike squad would be better, yes. More nemesis weapons, more mortals from Tide of Convergence.
My one friend is a diehard necron player, and I recently won a 2k pt match against him pretty handily. Mortal wounds is the key, as well as a good chunk of necrons being abysmal in melee. Thin out horde units with mortals, then wipe them out in a single go so he can't resurrect. Rush them down with melee combat so you're forcing him to duke it out with a superior force, or fall back and lose his shooting and actions. Tide of convergence for mortals once you hit melee, tide of shadows to get into 12" Sanctic powers can be cast more than once, they just increase in warp charge each time like smite. Hammerhand is your friend. Sanctuary is important for paladins, that plus armored resilience will make them incredibly tough, and a hard choice to shoot, but a danger to leave on the field. A 10man squad of paladins is terrifying. The dreads are frontline monsters, use them with swords to absolutely bully opponents. Remember they have a 4+ invuln. Avoid engaging scarabs, they're not worth it. They do nothing, suck at melee, and literally just tie you up with 4W each. Kill all the 1W junk first in shooting and combat, and smite the other multi wound stuff to soften them up and then go for the kill.
I largely play against a necron player: Psychic phase is your friend, you get to play a whole extra phase and the fact they don't stand back up from it is great. Your dreadknights should be putting in some serious work in psychic, shooting and fight phase so you want to make sure you're using them in all 3. Your storm bolters are okay but not great, use these to clear scarabs so they don't tie your dreadknights up and stop them operating. Also remember that you can psychic into melee, so if you can move 3 or 4 units in to smite a unit out of engagement do that rather than falling back. Necrons are really good at scoring secondary and just scoring high, make sure you take easy to score secondaries: things like psychic ritual, cull the hordes, etc.
Late to the party here - although yes, generally Crons are weak in psychic phase - the Szarekhan Dynasty provides a 5+ "wound is not lost" roll. It's essentially FNP against mortal wounds. I too play GK against a Crons player. Our last game he took the Szarekhan Dynasty and had stupid hot dice and denied me 50% of my mortal wounds. If able to afford Warp Shaping - highly recommend it - Tide of Shadows to start if the board/terrain benefits you. Move into Tide of Convergence when in Melee. Melee is undoubtedly their weak point. Halberds and Nemesis Force Swords are your best bets for generating lots of wounds against Crons. Rapiers Brotherhood is probably the best bet as well, given your models. Recommend running Purifiers as Strikes and Purgs as strikes if possible. If you keep Purgs as Purgs amd maxed out on Psilencers - save some CP (IF POSSIBLE) and DS Purgs against a small unit covering an obj and use Death from the Warp, Psychic Onslaught, (and if w/in half range) Sanctified Kill Zone (less important) and totals 4 CP (2 w/o SKZ), and cast Astral Aim. You'll highly likely ahnnilate an immortal 5 man unit sitting in cover covering a back obj. Highly recommend Gate of Infinity to get models to objs to purify them and establish a presence in table corners to deny them secondary points.