Replace zammy book with antidragon fire shield and you're good. 20 Antifire pots are ok, as long as you have some fires and nats to alch things. Pots last more like 6 minutes, and you can kill 3 or 4 dragons in that time. Use enchanted emerald tipped bolts until the dragon is poisoned, then switch to regular mith bolts. Goes really fast. For a single task of irons (40-60) you will need maybe 6 pots? I always take extra just in case.