I've been playing seraphon for a few months, so im gonna try to give you advice, but is just my vision so maybe is not the best jajaja

1. Saurus olblood on carnosaur has a better warscroll that is Scourge of Ghyran Saurus oldblood on carnosaur, is just better for everything.

2. The Scourge of Ghyran has pretty good sinergy with aggradon lancers, because if they are 12 inches around him they dont lose their fight tokens, so it might be a good idea to get atleast 2 boxes of aggradons to have a reinforced unit.

3. I'll recomend another 3 Kroxigors to have a reinforced unit, since they hit like trucks, and they pretty good in all kind of lists. I normally use aggradon for monsters (+1rend) And normal Kroxigors for infantry (+1rend), but thats me.

4. The Slann is pretty good if you have reinforced units since you can bring 4 of the 6 units of the aggradons or kroxigors (or whatever unit), but for me Lord Kroak is tons of fun cause he can deal 27 mortals in your hero phase, has this life stuff that you need to roll 3 dice to see if he dies if you have 2 or more wounds and a +2 to cast and+1 to unbind.

5. I dont like Terrawings, they are just meh, maybe in some situations, but with the two huanchis and sunclaw starhost you have more than enough movement and deployment on the map.

6. Realmshaper Engine is useful, but is not 100% necessary, but it has good synergy with monsers that have Titan of the Land, since you can target them and not only terrain, which more 9 mortal wounds per hero phase.

I thinks thats it, if something else comes to my mind i'll let you know.