I'd be worried about Anti Armour, and dealing with long range or indirect threats like HSS, Scorpius, Recons with Nemesis. I know your adapting models you have atm. I have recently brought 2 lascannon Javellins and a scorpius into my lists, its under 350 points but covers a lot f blindspots and does good work.
If your adapting the Age of darkness box, you could consider taking some of your points on slayers/stalkers, and building some seekers that can infiltrate and help manage backline threats, or converting some to be recons with nemesis bolters.
For Anti Tank/Dread, if your getting the box, then the contemptor is a must include either with a melta or lascannon that will help dealing with armour and heavy infantry.
On your Varagyr, you should consider maximising their loadout to include Thunder hammers and frost claws for an extra attack and flexibility in target.
Overall I'd significantly reduce the amount your spending on the troops to help you cover other bases. You can get much the same effect from massed despoilers. If your doing 15+ troops in a unit consider apocatheries.
Lastly, we all love the speaker of the dead, but he's a bit wasted on Varagyr, they don't need the hatred re-roll as they'll be ws6 on the charge, and they will likely be fighting other terminators or elites that will bring Instant Death weapons that will negate his Feel No Pain.
One alternative would be 20 of your slayers/stalkers in the spartan with the speaker as they will really benefit from him. And freeing up points for a warmonger centurion to go with your varagyr. He will give them deepstrike to avoid foot slogging. Then Russ can take advantage of his speed on foot.