I know the Slann can't use Transformation of Kadon, how about Tehenhaun the Prophet of Sotek? Pann's Inpenetrable Pelt and Savage Beast of Horros are cast on a friendly character. What if the character is mounted? Do any of the bonuses from either spell every carry over to a character riding a Terradon, Cold One, Carnosaur or Stegadon? I'm guessing it's no but I'm looking for excuses to branch out away from the Lore of Life, Light, and Shadow. I also have a tendency to use a lot of characters so I thought the lore of Beasts may be an adequate choice. That and I like the Tehehaun model. EDIT: Does the Wildheart bonus apply to a unit with mixed troop types? Would a mounted Scar Vet in a Saurus block make it count as cavalry for the purpose of that bonus?
Slann cant use transformation because they are not technically on foot. Tehenhuan is on foot so I would say he would be fine. He would probably lose his swarm of snakes while he is transformed though. The spells target the character specifically. The mount would not get the bonus. A mounted character in a block of infantry does not make that block a mixed unit or cavalry. Wildheart wouldn't apply for any spells that target the unit as a whole.
Tehenhaun Can use it if you didn't give him the stegadon, and like he said the snake would dissapear while he was transformed, i would immagine.
In one game, I took a beasts slann with plaque of tepok and Tehehuin. That way, I assured that I would get Transformation of Kadon on Tehehuin. I tried that entier game to get that spell off and never did. It was not worth building the army around it.