Just hit CP600 & looking to respec my CP to be a bit better (Blue)

*Edit: Dark Elf Magicka Nightblade*

Thinking of going:
Ritual:

• 31 Thaumaturge Increases your damage done with damage over time effects by 13.13%.

Atronach:

• 56 Master-at-Arms Increases your damage done with direct damage attacks by 20.15%.

Apprentice:

• 37 Elemental Expert Increases your Flame, Frost, Shock, and Magic Damage done by 9.09%.
• 20 Spell Erosion Increases your Spell Penetration by 1900.
• 56 Elfborn Increases your Critical Damage and Critical Healing with Magicka abilities by 20.15%.

My setup is 2 zaan 5 siroria 5 mother's sorrow
Just wondering if anyone has any better suggestions? e.g. I know some builds use staff expert for LA/HA damage, but I figured this was just any spare points, plus I'm still farming the vMA staff.
Some posts I've read say put as many points as possible into MAA since main damage comes from here. Others say AoE's are the best source of damage...

I've gone with 20 in spell erosion since my pen sits at just under 7k, which after the 10k debuff from the tank puts me 1k off cap.

*Edit2: Reason for asking is I want to make sure my CP is optimal before I pour time into my rotation*

Thanks in advance