Need help rounding out my 50pt army

[rydar666]

I need advice on what unit to add to my list.
My current list (models owned) -
Ravyn +6
Phonenix 10pts
Phonenix 10pts
Phonenix 10pts
10 MHSF 8pts
MHSF U/A 2pts
MHA 2pts
MHA 2pts
Narn 3pts
Eryss 3pts
Arcanist 1pt
Arcanist 1pt
Ghost Sniper 2pts
Ghost Sniper 2pts

What I want to do is be able to drop out a 'jack and add in another unit.
I'm considering Invictors, Sentinels or Halbardiers. Which unit would serve me best in regards to syngery with the rest of my army?

[ChadeFIN]

From my experience Invictors mesh very well with Ravyn. Give full squad of them UA and cast snipe. That's 18" range even without moving. Combine with Ravyn feat for pure awesomeness.