Lets start talking about the elephant on the room. Chamaleons, solar engine and terradons. These 3 units are undeniably good, but i think the only one of them that diserves nerfs are terradons, as they are the unit that has more impact on the battlefield if the oponent is not prepared. For that reason, terradons (600 cost variant) should be nerfed with -3 or -4 ammo.
Concentration instincts- This is just a worse version of cold blood. Plenty of games were there is actually no reason to click on this ability. It should grant +5 LD on an AoE.
Tiqtakto´s blade of ancient skies- Cant insist more on how bad this item is due to how easily air combat can be avoided or if the oponent doesnt bring flyers at all. I think a good idea would be to make the item grant less stats, but Tiqtakto keeps half of the stats when he is on the ground.
Tehenhauin- Serpents´ tongue blade should be better due to Tehenhauin alredy having poison by default and how prevalent poison alredy is on Lizardmen roster. Either increase AoE to 55m or increase charge bonus buff. Also, -50 cost to stegadon mount.
Nakai- Give him inmune to psychology, -50 cost and increase duration of primal roar +3 secs.
Terradon mount for skink chief and skink priests- Give them vanguard deployment for game consistency and because there are arguments to make about it being slightly overpriced.
Ark of Sotek- I think the diameter of the vortex is quite small taking into consideration how easily enemy units can get out from it and that the Ark has to take some risk diving on enemy lines to place it correctly. So +20% diameter increase on vortex.
Revivification Crystal and Engine of the Gods- Would be nice if these units didnt stop moving while using their bound abilities or if their cast time was a bit faster.
Salamanders and Razordons- +8 HP per model. The main problem is how fast they bleed models for their price paired with how microintensive they are because of their range.
Ancient Salamander- +200 HP.
Sacred Kroxigors- +2 MD.
RoR Sacred Kroxigors- +15 % missile resistance, -5% physical resistance and +50 cost.