Discussion about the Sanctuary faction.

many players choose two squads of Luminaries in duels, but then only Tsunami works.

It's quite difficult to level up before Tsunami in a duel. Mostly, duels take place on "Far Bridge," and even at level 10, it's unlikely you'll reach that point. And single Luminaries are powerful; they dispel everything.
Regarding the topic, I'd like to ask the experts about the tactics for Sanctuary against Barbarians (Tribes) on this map. The opponent is a power-based player (their favorite tactic is to push the enemy and use Drain), and their army consists of upgraded Harpies, upgraded Orcs, single Goblins, and sometimes a couple of 4-5 Centaurs. That's all. I have Kappa, Water Elementals, Sharks, and Yukionna. Unfortunately, the high cost of units makes it very difficult to build Centaurs. It's possible (with luck and if the "equal resources" option isn't enabled). Dynasty bonuses are disabled.