All the walkthroughs tell me to use the stairs on the side of the piramid to get in to the first one, but the bottom is broken and I can't jump onto the ladder
Try going around to the side of the pyramid with the little shack. You'll see some hand and foot holds in the wall there. Make your way up and you'll be in. Watch for spiders.
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Hey, it's my turn to pull off the mask, Scoob.