If another ability of a source you control triggers when attackers are declared, such as that of Hamlet Captain, you may have it resolve before or after that of Hanweir Garrison or Hanweir, the Writhing Township
Plus, if you can get something onto the battlefield, their battlefield is often lacking any real threats until the midgame, letting you go on the offensive uncontested
Do not fear the lightning
Its attack trigger lets you draw a card for each attacking Dragon and then put any permanent from your hand directly onto the battlefield for free, creating an avalanche of value that is nearly impossible to come back from
Outside of something like Cranial Ram, though, there's not too much that's looking like it's going to be a major issue from the jump