[quote=@GreivousKhan]
I'll assume the castle has a Sally port. What castle doesn't?  
[/quote]

Almost certainly going to be watched though, so will still require speed to be unseen. Speed, trickery, or a diversion. An exploding diversion. If you want to also collab a loud boom of some kind from across the battlefield, I can happily make sure that happens in the collab between [@Sypherkhode822] and I.