The last time I attempted to run Expedition to Castle Ravenloft, the heroic party looked at the tall looming castle and formulated what they thought at the time was a clever non-confrontational strategy. Excessive use of Stone Shape to open holes in the floor and constantly send non-flying creatures to floors below them, and seal them up right after and continue exploring.
Which presented quite a problem when after the top spires were explored, they realized they'd have to journey into the sub-levels where they kept sending every horrific creature which was surely still lurking and plotting.