I would run something along the lines of this: Allegiance: Seraphon LEADERS: Slann Starmaster (260) - General - Command Trait : Great Rememberer - Artefact : Incandescent Rectrices Skink Starpriest (80) - Artefact : Light of Dracothion Units: 6 x Ripperdactyl Riders (280) 40 x Skinks (240) -Boltspitters & Star Bucklers 10 x Skinks (60) -Boltspitters & Star Bucklers 3 x Razordons (120) BATTALIONS: Shadowstrike Starhost (180) TOTAL: 1220/1250 EXTRA COMMAND POINTS: 1 WOUNDS: 88 You can bring whichever affordable endless spell you like most. I often choose Malevolent Maelstrom when I have 20 floating points. Many armies rely heavily on spells and if you get MM off it has the potential to cripple one or more turns for them. The artifacts are also pretty flexible. Alternatively you could drop the Razordons and forego an endless spell to add in a Saurus Astrolith Bearer.
You are correct, I am bad at math. I think you are better off with the Razordons anyways. lol. You can already reroll hits and wounds of 1's from the Trap is Sprung battalion ability and your Rippers will be swooping while your main Skinks will have the 40 man bonus. Not that d3 extra Celestial Conjuration points isn't nice.
Based on my current army building trends I would suggest: Allegiance: Seraphon Mortal Realm: Shyish Slann Starmaster (260) - General - Trait: Great Rememberer Skink Starpriest (80) Engine of the Gods (220) - Artefact: Ethereal Amulet Engine of the Gods (220) - Artefact: Sepulchral Plate 10 x Skinks (60) - Meteoric Javelins & Star Bucklers 10 x Skinks (60) - Meteoric Javelins & Star Bucklers 10 x Skinks (60) - Meteoric Javelins & Star Bucklers 6 x Ripperdactyl Riders (280) Shadowstrike Starhost (180) Chronomantic Cogs (60) Soulsnare Shackles (20) Total: 1500 / 2000
There are some shadowstrike builds in this thread: http://www.lustria-online.com/threads/all-around-best-2k-army-list.21828/page-2