So I went ahead and fought the battle. It was my two armies (well-mixed composition) against the one with 8 carnosaurs, 8 stegadons, and a couple characters and fliers, and a second that was only maybe 1/2 dinos, with a whole bunch of fliers and a couple ground-pounders.
The initial disposition was… interesting. I was hoping to bait the dinos to me with some ranged units and then sandwich them with my reinforcements, then turn on their reinforcements (standard tactics, I guess). Unfortunately I put my main army too far back up the hill, and almost had the reverse happen to me. Fortunately, they split their main stack and sent some dinos and flyers at my main stack and the rest, together with the reinforcements, at my second stack (which was already weakened from previous fights).
At this point I’m feeling pretty pessimistic, especially because most of my dragons were at half health (from previous battles). I rushed down my main stack and meet their dinos with Phoenix Guard, White Lions, and dragon breath (as well as some Sisters and Sea Guard ranged support).
The second stack had the 2 bolt thrower batteries, which focused on one dinosaur after another, as the Phoenix Guard got overwhelmed by multiple dinos and the Sea Guard (and archers, sadly) struggled with a dino charge each. The cavalry ran around trying to get some charges in where possible, and the chariots tried to find the skirmishers and infantry in the enemy reinforcements. I flubbed the cavalry management a bit (let them get charged) and was too indecisive with the dragons.
Meanwhile the Guard and Lions of the main army were making good on their dinos. I foolishly let a sun dragon chase their flyers a bit, but I don’t think she was too injured by their flaming (ranged) attack; once I put the archers on them, they ran away quick enough. I mobbed their toad mage (not the main general, alas) with a pair of dragons and some dragon princes; that worked well to shut down their magic support.
At this point I’d handily won the upper engagement and was about to lose the lower. The dragons and cavalry from the upper battle rushed their general and a dino it two that was hanging back. The last of my troops from the lower battle left the field (some by my command, some not). Just as my main forces made it in range of their remaining (combined) army, they gave up the fight and fled, and I chased a couple units down.
In the end I lost four units completely (from the lower army)–a bolt thrower, a silver helms, a Sea Guard and those poor archers–and I further combined two Sea Guards. The rest of that army was at 20% health, while the upper army fared considerably better (but still took some hits, to be sure). They lost a bit over half of each army, but I was in no condition to pursue the remnants into the castle they retreated to.
Where I did well:
I mostly managed to bring the right units into contact with their dinos. A couple Net of Amyntok casts we’re pretty clutch.
Where I did poorly:
I need to get better at managing cavalry and chariots.
Where I got lucky:
The AI divided their forces poorly, and didn’t cycle-charge with their dinos. I managed to pull a dragon out at 5% health.
I was very pleased with the performance of my Phoenix Guard and White Lions, but really I underestimated both my dragons and my low-tier troops.
(This was on normal battle difficulty.)