I'm telling you, teleportation isn't a luxury, but just a means of movement :D. It's the same type of movement as flight. Therefore, it shouldn't be better than others.
If dragons can only fly to the unit standing opposite them, why should devils have the advantage of being able to attack any unit at the beginning of the battle? Then they should be made as strong as bone dragons. And I don't think "summoning lords" will be a thing anymore – it's a different part of the game, after all.
Overall, several types of damage would diversify the gameplay, but I definitely can't imagine poison damage.
Демократия есть одурачивание народа при помощи народа ради блага народа.(Уайльд Оскар)