Originally Posted by
Kensagaku
You've got the basic strategy down for soloing it. Generally, you'll want a few worms as a "last line of defense" and then sic crabs and colibri while you go build enough Puissance to summon a Shijin. They can change the battle, and of them all I recommend you use a Eudaemon Sash for your statue to get the Kirin Shijin (if I am remembering this correctly), which will absolutely wreck things. Also note that the Valiants cannot destroy the enemy Stronghold; they can get it down to a single HP, but a player must deal the final blow to destroy it.
Keep at it. :)