>Tournaments: Treasures of the Sands

In my opinion, Ora, Vittorio, and Sinithar can compete with Letos.

I would like to ask right away, what criteria were used to create the cards? Was it based solely on the strength of the heroes, or were possible counter cards taken into account?

Approximately like this: Attacker, Defender, Universal.
As much as possible, of course. The heroes were also distributed as evenly as possible in terms of "strength." And so on.

A tournament is not an indicator of skill, nor is it an indicator of anything at all. A tournament is for playing. It was. Well, never mind.
Don't worry, it will get easier.