Update 3/3/20
Looks like GW has decided to bless us with some rule previews this day, here is a short and sweet list of the changes we can see. (ok maybe not so short as i was thinking...)
Allegiance abilites are being split up between two major factions: the Starborne and the Coalesced,
there are two abilities that are shared between the two factions and those are:
Contemplations of the ancient ones, our basic slaan spellswap and...
Sacred Asterisms. seems to be an unbound version of our slaan's celestial configuration ability, they mention that they are changing it to allow choosing a certain constellation and to allow specific units to recieve it, no idea if you can choose multiple units to recieve different constellations.
the first ability seems to indicate that slaan will still be the main focus of spellcasting in our army (go figure), but freeing our constellation ability allows for perhaps a viable no-slaan list to be made.
As for specific abilites for our two major factions...
For the Starborne we have our typical LoSaT, summoning, and bravery 10. LoSaT is being changed to trigger at the end of the movement phase.
No more dumping endless spells in the enemy back line then fleeing to safety with great rememberer, but this may allow us to teleport summoned units in the same turn! all in all it seems to be the same seraphon we have had for 4 years just with some properly updated rules, which is totaly fine! i know some people like playing the objective game with this army so its very nice that they will still have the army they fell in love with.
For the Coalesced we can expect a much more ferocious combat ability from our space lizards, with the ability Predatory Fighters you get an extra attack with any
Jaws weapon profile, this applies to
ALL units in a coalesced army. They also get the ability Scaly Skin, allowing you to subtract 1 from the damage of attacks that target your units (to a minimum of one of course.)
With these two abilities we can see the Coalesced are ment to be our savage side, with the extra Jaw attack obviously geared towards saurus units such as our knights warriors and guard, however
in the subtext of the WarCom post they mentioned that the Predatory Fighters ability will affect many of our units like "Saurus, Stegadons or anything in between" lets hope this means some of our monsters will receive an extra attack profile to use in melee. Also Coalesced armies will be immune to bravery modfiers and negative terrain effects while "on your table half." i can only presume they mean in your territory but if they actually mean half the table this could be a very powerful tool against armies that have some nasty plays surrounding bravery.
we also were previewed a few sub-factions. its been said that each of them provide an ability, command trait, and artifact. and some provide a command ability. no word if the traits and artifacts are mandatory per faction though i think its a safe bet they will be.
Dracothion's tail is the first faction previewed, showcasing an ability that is almost word for word coppied from the batallion available in GHB 2019, but instead of deepstriking units in the hero phase near
THE slaan it now happens at the end of the movement phase near any slaan, still up to half of your units can be held in reserve and they must still be set up within 18" of a slaan.
Next up is the Fangs of Sotek sub-faction, being more skink focused it gives all
skink units +3" to their movement in the first phase. once again similar to the battalion but only effecting skinks and skink units like terradon/ripperdactly riders, the bastilidon and the stegadon (assuming they keep the skink keyword.)
for our lovers of saurus CP spam we now have the Koatl's Claw Faction. the ability giving a +1 to hit rolls for saurus units that charged in the same turn. and a command trait that seems to give an aetherquartz brooch to your general, you roll a dice each time you "issue a command to a friendly koatl's claw saurus unit." and on a 4+ you receive 1 extra command point. finally all your wet dreams of having a carnosaur with 30+ jaw attacks could become reality given our oldblood on carnosaur's command ability doesnt change (it probably will, sadly.)
Last but not least is the THUNDER LIZARD faction "lets you field armies of nothing but super-durable Stegadons." no actual rules are previewed in the post but we can look forward to that later this week.
Thats it for sub-factions and allegiance abilities for now. we got some info on another changed warscroll or two! the skink oracle on troglodon is being changed in a major way, it will now be a wizard with +1 to casting dispelling and unbinding! (is it sad that this already seems better than our current slaan?) in addition to that they will be able to unbind and dispell with infinite range same as the slaan! and if that werent the icing on the cake they are also getting kroaks Comet's call spell. with all this magical potential on a mere skink i can only dream the new heights our magical toads have reached... next we see some buffs to our saurus warriors in the form of -1 rend on their clubs and changing their ordered cohort ability to be 1+ attack with their celestite weapons at 15 or more models, no more +1 to hit for massive units bonus. but this may make it much more viable to run smaller units of warriors.
One last thing we are finally recieving the "magical supremacy" that we have longed for, in the form of "bound endless spells", basically regular endless spells but predatory ones only obey YOUR command! ... i really hope there is more to this but at the moment it seems like that is all we know on the matter.
well thats it for this update i look forward to hearing more about this thunder lizard faction allowing stegadons as battleline, though i hope it isnt restricted to them, i would like very much to run my turtles as battleline as well!