Yes, the Thunderlords deserve credit; they are strong. But, in my opinion, it's better to shoot than to use the cloud spell. Think about it – you're just taking away a shot from another archer, but you're also taking away a shot from the Thunderlords, who might have already taken down enemy archers.
The Rainbow Dragon was named the Crystal Dragon. It's a bit strange how they translated it; it seems like it was originally written as Rainbow Dragon, which means Rainbow. But the translators translated many things strangely in the game.
What do you all think about the Red and Magmatic Dragons?