me being dumb i'm not too sure what you're asking....
but tantalibsdjfhsdjgklhsjklg (can't spell it!! :rolleyes2 ) is pretty easy. just keep casting with vivi as often as pos, keep him alive. plus only really do big physical attacks when its open. you can open it by doing normal attacks and if the hp adds up to a certain number (which i forget...sorry!) it will open!