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Message: <blockquote data-quote="MatthewJHanson" data-source="post: 8023784" data-attributes="member: 13968">In the gaming I'm DMing, the heroes are exploring a trap filled dungeon, and have correctly guessed that there is a giant boulder trap at the end of a certain hallway (based on Rolling Sphere from the DMG, but upgrade because it's a 15-foot sphere instead of a 10-foot). They have an immovable rod, and plan to use it to block the giant boulder.I'm considering letting it just work because its called an immovable rod, and because I like to reward smart play. The thing is though, that according to the book, the immovable rod actually has a weight limit of 8,000 pounds. I did some quick calculations, and a 15 foot diameter sphere of granite should weigh nearly 300,000 pounds. That's way more than the rod can hold, but I also figure the stone wouldn't be putting its full weight limit on the rod. I'm pretty sure there's a way to calculate the force of the boulder on the rod, but my physics skills are rusty. (Also intuitively I feel like the current speed should factor into it, not just the acceleration).Both the rod and the sphere can be thwarted by Strength checks, so I'm thinking about having them make some kind of opposed check against each other or something like that.I don't just want to do a gotcha on my players. My goals are to have fun encounters and encourage clever gaming. With that in mind what would you do?</blockquote>