Lobster

Ironman verdict

At least 9 monsters drop it. The easiest is Sanguine crawler (level 43, 10/128); the best rate is Greater reborn warrior (level 82), at 17/100, about one every 6 kills. You can also make it yourself: it takes 40 Cooking and gives 120 Cooking XP, using Raw lobster. Other sources include Gourmet impling, Baby impling, Baby impling jar and Gourmet impling jar, plus 4 more listed below. Making ten takes 10 × Raw lobster and gives 1,200 Cooking XP. Reaching level 40 Cooking takes 37,224 XP in total; the Cooking calculator counts the actions and materials to any target, and the Cooking guide has the Ironman training route. 2 recipes use Lobster, including Attuned portent of restoration V and Portent of restoration V. Lobster 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 160 coins, which is 108 less than the shop price, so buying it to alch does not pay.