I'm not too experienced but i can share some of my thoughts of good and funny combos.
Gravespawn command ability + titanic fury: will make your ghorgon a dmg monster with 7 attacks with 3 dmg, and 3 attacks with D6 dmg (require chaos spawn though)
Gavespawn artifact + brass despoilers; makes up for the drawback on the artifact (i use it currently on my doombull; 3 attacks, - 2 rend, 5 dmg)
Make shaggoth a melee monster: Lightning-fast monstrosity + Lightning-chained Bracers; (cast spell on self) will make him go first in combat (if charged) and reroll all hit and wound rolls.
Commanpoints forever, you will have many bray in your list and by giving shaggoth ancient beyond knowing and a shaman with The knowing eye, you can run and charge (brey stuff) so consistently by spending CP for run- and charge-rolls. CP; Begin with 1 +D3, get 2/turn with a 50% chance.
My favorite spells: (brey) savage dominion and titanic fury. (Thunderscorn) hailstorm