Erephir in the third line, so that he can attack the enemy if necessary. In the second line, some kind of sorcerer, so that he doesn't have to run too far. Closer to the rear – Koshmara, he will reach it anyway. And Orena closer to the center, so that he doesn't get lost immediately.
By the way, if the sorcerer has restored his mana, he would also be a good choice for the tank. He is especially effective against annihilators, thanks to his mana shield.