You get Ice Spreader in Magmoor Caverns, See where it says upgrade on this map and then see where it says Ice spreader. Well go to that room and use your power bomb to destroy the wall and underneath you will find the Ice Spreader.
It's somewhere near the monitor work station. I think. You need morph ball power bombs. You go through one of the many doors out of the area. There you will see one of those tunnel/bridge things that look broken down in the middle. Use a power bomb there and it will break apart. If you're going out of the monitor work station: jump to your left. If you're going towards the monitor work station: jump to your right. It's right below the bridge/tunnel.
