How do you create complex chains of elementals?

I must say, it's a complete failure... You wouldn't attack 3 Ents instead of a crowd of archers just because of the double damage.

Yes, the ability is quite controversial. I still primarily aim to neutralize the most dangerous opponent, regardless of their element.
But overall, the bonus is good, especially if you have many cities and many altars. I remember playing on a large map and capturing 5-6 Elven castles, dealing several thousand additional damage.