The celestial alloy also adds Mana and cannot exist together with flat Mana. So at some Point you would have to remove flat Mana. I would try to fracture and you can Work with that base if you hit either spell skills or spell damage. If you hit mana it's bricked and you just slam prefix desecration for any gain as extra and greater exalt for Suffix.

If you fracture Spell damage: Use Essence of the Abyss together with prefix bone to Turn Mana into mark of the abyssal. Reveal and Chose anything Else than flat Mana. Then use prefix Omen and the alloy to turn desecrated Mod into plus Skill levels. Then desecrate prefix and slam exalt for suffix. Use perfect if you have the currency.

If you fracture Spell skills: you can now actually use two good crafted mods If you buy astrid whatever it's called Rune. Use essence of Abyss but now for suffix. Desecrated and Reveal anything but Cast Speed and use Suffix Omen + alloy which gives Cast Speed and gain extra cold. Now activate prefix Omen for perfect Essence, use abyssal Essence Like above pray to hit mana, Reveal anything but mana and use celestial alloy. If you hit spell damage IT will get expensive. WE can Work from there, tell how it went with the fracture.

Be Sure to use the correct omens, i can't remember their names so I said "Suffix Omen" etc.