Replace Alpha's Howl with Vertex.
Divine amulet and grab Efficient Inscriptions notable if you want to keep CoA, otherwise swap to Elemental Invocation if you want to keep a trigger for Living Bomb or drop Blink. Drop Arctic Armour, move Khatal's Rejuvenation support to Life Remnants as that has no Spirit cost to be multiplied. Dialla's Desire to replace one of your comets if you want to fix spirit without needing to divine amulet, otherwise Zenith ll or Uhtred's Augury if you can afford it.
Use as low level Living Bomb as you can to avoid situations where you lack the resource to cast comets.
Impending Doom cluster on passive tree is useless with Windscream, or drop the boots and get no more than 29% faster curse activation through two jewels.
Upgrade your Covenant to one without the gain life cost equal to mana cost to further reduce life costs. It will be much better even if you don't get one with % life cost efficiency. Make sure it still has the leech of course.
Rakiata's won't help as you are already using elemental weakness.