Coal

Ironman verdict

At least 7 monsters drop it. The easiest is Dwarf (level 9, 2/128); the best rate is Desert lizard (level 30), at 13/128, about one every 7 kills. You can also make it yourself: it takes 24 Divination and gives 6 Divination XP, using 2 × Bright energy and 5 × Iron ore. Other sources include Managing Miscellania, Concentrated coal deposit, Bandit (Wilderness) and Squeal of Fortune/Rewards, plus 4 more listed below. Making ten takes 20 × Bright energy and 50 × Iron ore and gives 60 Divination XP. Reaching level 24 Divination takes 7,028 XP in total; the Divination calculator counts the actions and materials to any target, and the Divination guide has the Ironman training route. 7 recipes use Coal, including 'Perfect' coal, Barrel of naphtha and Elemental bar. Coal is available on free-to-play worlds too. It is tradeable on normal accounts, but an Ironman cannot use the Grand Exchange or trade for it, so the sources on this page are the whole list. High Alchemy turns one into 25 coins, which is 17 less than the shop price, so buying it to alch does not pay.