Wave 12 is the next wave wave and i reccommend a few tactics. Get a few bannermen to help you get points while you hold off the enemy for a while. As soon as the first Orc Shaman appears, buy a non-magic using character to kill him. Try saving points and buying mutiple elves at once to overwhelm them. . Use a melee character with high damage stats or high health. Or you can use a ranged character if you have torchbearers on the field (make sure to protect them). You may need to get good wall upgrades in case they fall. Use repairmen if the enemy is busy to heal your walls.