Starcannon is absolutely terrible. Bright lances are extremely expensive. Your farseer is too expensive, you have no units benefitting greatly from guide.
I would make the wraith lords + farseer much cheaper to get another
MC in. Ex:
Avatar (155)
Farseer, fortune, RoW, RoW, spear (113)
10 Wraithguard, spiritseer, conceal (396)
10 Guardians, shuriken cannon (85)
Wraithlord, 2 flamers,
EML, sword (125)
Wraithlord, 2 flamers,
EML, sword (125)
(999)
This army should do very well in
KP missions. The guardians are the softest
KP, and when reserved and played defensively, it is hard to take out 10 guardians.
In objective missions, the guardians reserve and score home objective while the blob and friends go hunt enemy/midfield objectives. 10 Wraithguard can hold several objectives and will be very hard to shift. Their main issue is close combat, and with the avatar and two wraithlords to back them up, there is little that can actually touch them. Even assault termies will get knocked around.
The list lacks long range anti-tank, but then again, so does the initial list. 2x more brightlances for 80!!!

pts does not anti-tank make. Both the avatar and the wraithguard are dangerous to tanks at 12" though, and everything but the guardians will rip apart tanks in close combat.
Russes are not scary for this list. Proper spacing means they can hit 3 wraithguard with a blast. You will have 4+ cover most of the time and at minimum 5+ cover. Guard also can't stop fortune, so that means that 0.6/1.1 wraithguard die per S8 AP3 big blast that hits. 2 russes that hit every turn will use 5 turns to kill the wraithguard if you do not have proper cover.