Full disclaimer, I am fairly new to AoS (and am running with a limited model pool), so take my lists with a grain of salt. Allegiance: Seraphon - Constellation: Thunder Lizard Leaders: Skink Priest (80) - General - Command Trait: Master of Star Rituals - Artefact: Fusil of Conflaguration Skink Starpriest (130) - Spell: Hand of Glory Battleline: 20 x Skinks (150) - Boltspitters Celestite Daggers & Star Bucklers 20 x Skinks (150) - Boltspitters Celestite Daggers & Star Bucklers Behemoths: Bastiladon (235) - Weapon: Solar Engine Bastiladon (235) - Weapon: Solar Engine Faction Terrain: Realmshaper Engine Endless Spells: Burning Head (20) Total: 1000 / 1000 Extra Command Points: 0 Allies: 0 / 200 Wounds: 69 You would need to take a Linebreaker battalion to fit the Bastiladons, so a free all out attack or all out defense to cover your Bastiladons seems fine to me; and the rest could fall under either a vanguard, or battle regiment. Not sure which one I would prefer. I would be tempted to go with a vanguard battalion if I shifted the skinks into 10-man and 30-man squads instead of an even split. Let me know what you think. I am likely to be playing a 1000 pt match this next week against Nighthaunt, and I want to try and figure out where I need to go with my list.
Skink Priest costs 80 Points and Skink Starpriest costs 130 points in AoS 3.0. You could just take out the Endless Spell: Burning Head and all would be fine again. List looks fun, possible change could be a Scarvet on Cranosaur (215p) instead of a Bastiladon (235p), with the 20 points you get you could field the Burning Head again if you like it.
Oops, I was copy pasting an old list and forgot to change those values! It should still math out to 1000 exactly with the burning head in. Let me fix the post real quick...