Tactics against Haven and Dungeon.

Well, rushing has always been a standard tactic against Chaos. You can also force Chaos to constantly defend. In this case, Sylvan can do a lot of nasty things by using creature summoning and calling them into battle.

It would be good to gather as many resources as possible that are lying around unguarded, which the Chaos thieves haven't collected. Resources are essential for Chaos, so you need to prevent the thieves from roaming around.