I would recommend dropping the Deathmarks and Doomscythes. freeing up 500 points and i would use:
I would replace with 1x Monolith.. deepstrike behind enemy lines and get your warriors in close for rapid fire guass from behind. 200 points
Give wraiths all whip coils.. Initative 5 in combat meaning they most of the time hit first even when charged and only 3 points a model worth it. extra 18 points for the unit (6) Wraiths
Give your warlord nightmare shroud (2+ armour save) with the phase shifter 4+
inv save and 4+ ream save from the formation. makes him hard to kill. 35 points
Third squad of warriors would help you in objectives and firepower extra 10 shots at 24" or 20 at 12". Glance/ wound any target on a 6+ regardless of the stats due to gauss rule, makes dealing with dreadnoughts and wraithknights much easier. (glance to death) 130 Points
Second Squad of immortals would be good for sitting on objectives and having long range guass too. 85 points
with your 1st immortal squad i would change them to guass too. but its donw to the army you playing against, Armour = Gauss, Horde = tesla
then with that gives you 32 points left to spend but makes your army much for deadly and quicker.
remenber with your Havest and Reclamination legion you also get the Decon Legion rule too from the codex page: 62-63 gives both formations 4+ reanimation
Hope this helps