For Chisel

Use Chisel to destroy ice. Crypt-contaminate can find a chisel. Test run and simulchip can reuse chisels from the heap. To further reduce the strength of ice, use Null, cookbook, ice carver. Use your icebreakers to cheaply break low strength ice. Use Imp and Turning Wheel to access / trash more from centrals. Earthrise Hotel gives cards to use for Null's ability