When playing a mission with two or three Clans, you can defeat oncoming enemies rapidly by creating only ranged Goblins such as Archers, Hunters, Mortars, Savages, Mages etc. When the enemy is attacking, line your Clans of 10 into a line and wait for the enemy to approach. When in range, your Goblins will fire a volley or two and mow down most of the enemy without sustaining much damage.