Crude iron is one of the most common, one-star ingredients, needed by the forge to create Arrow Attack, Tornado, and Miracle Scroll.
Bonus Drop Chance:
- S1: Province 6, S1: Province 14
- S2: Province 12
- S3: Province 9, S3: Province 22
- Season 4: Provinces 5 and 20
Per Barry Farmz Here, S1:6-8 (or the whole province) is the most cost-effective with ~60.4 % chance.