I tend to play Sedna this way.

When working on a spec it is important to see what the DG abilities are and then maximize the benefits.  For Sedna this is HP regen, if you stack all of her HP regen abilities and then add more HP regen on items she is practially unkillable.

I usually start w;ith pounce as its a great skill to get DG kills, and make that coin that you will need for gear upgrades.

I then max out

Heal: Heals a target of its wounds, and damages its nearby assailants.

Silence: Enemies near Sedna are barred from using magical spells for a short duration.

Inner Grace: Increases Sedna's movement speed and health regeneration.

Life's Child: Sedna's health regeneration is greatly increased whenever her life total falls below 30%.

I am not sure if Healing Wind actually heals Sedna or only her minions.  But if it does this would be worth getting as well.

Speccing this way I am able to regen faster at level 10 than a tower can damage.  Plus if you get low you can always clutch heal to survive.