I think its from labyrinths in the twilight Forest. Edit: Woops, someone already beat me to it.. PSA:If you have the twilight forest and tinkers you can use steeleaf for infinitely regenerating tools if you have steeleaf in your hotbar For anyone playing E2:E yes it works there and its not gated also a block regenetates the same amount as 9 steeleaf so use them if you have more than a stack for faster regen.
钢叶 (Steeleaf)资料的介绍页面，此资料来自模组 [TF]暮色森林 (The Twilight Forest)，我的世界MOD百科，提供Minecraft (我的世界)MOD (模组)物品资料介绍教程攻略和MOD下载。. Steeleaf is a new item added by Twilight Forest. Steeleaf can be found in Twilight Forest dungeons and castles. All steeleaf tools have 132 uses, about twice the durability of wood, although armors made from steeleaf has varying durability. All steeleaf tools and armor become enchanted with a specific level two enchantment upon crafting (e.g. Fortune II, Feather Falling II) except for the hoe.