Crawler

Crawlers are the second cheapest units in chaos. In groups, they can be deadly, but they are very weak to splash damage, like bombers. Because of their low health, high speed and regeneration, when having crawlers in battle, you can pull out the injured crawlers from battle, and you can place that crawler back in battle after the crawler is healed.

simsim40's Stratergy
get 20 Crawlers with Pack Mentality and Predeatory Edge. Get a Marrowkai or Giant(Better to get both). If you get the giant then Stun your enemies and finish them of with the Crawlers. Make Sure to Concentrate ony at one unit at a time. If you take Marrowkai then make sure to have 1 or 2 Juggerknights. Reap the enemy unit and finish him of with the Crawlers. However Reaper only reaps one unit unlike Giant's stun. So to protect your Crawlers make sure to have Juggerknights protecting them.