Forbidden and Arcanus: Item Modifiers and Special Gear
Forbidden and Arcanus lets you enhance equipment with magical modifiers applied through smithing. This guide covers the modifier system and the gear it produces.
Applying modifiers
The apply modifier recipes use a smithing template plus a special component to grant an item a new power. The components include the 
Sea Prism, 
Terrastomp Prism and 
Smelter Prism, the 
Eternal Stella, the 
Ferrognetic Mixture and the 
Soul Binding Crystal — each imparting a different effect to the gear it is applied to.
The Blacksmith Gavel
The Blacksmith Gavel is a signature tool; upgrade a 
Diamond Blacksmith Gavel with a 
Netherite Ingot through smithing to make the 
Netherite Blacksmith Gavel, the top tier of the tool.
Building toward the modifiers
Most modifier components are earned deeper in the mod, from its structures and rituals, so treat modifiers as a mid-to-late goal. Set up a Clibano and a rune supply first, then pursue the prisms and crystals that let you tailor your weapons, tools and armor with the effects that suit your playstyle.
Modifiers are a six-recipe system
Apply Modifier carries 6 recipes on 1.21.1 and 5 on 1.20.1 — the mod's gear-upgrade path in its entirety. Alongside it, Smithing Transform has exactly one recipe on 1.21.1 and none at all on 1.20.1.
Seven recipes across both categories is the whole upgrade layer, which makes it worth learning in full rather than looking up piecemeal.
The rest of the mod is larger on the older build
Crafting runs 172 recipes on 1.20.1 against 144 on 1.21.1, and stonecutting 39 against 14. The Combine Residues system — 10 recipes — exists only on 1.20.1.
If a material step in a guide has no matching recipe in your game, the version difference is the most likely explanation, and it usually favours the older build.
The Clibano is the constant
15 Clibano Combustion recipes on both versions make it the reliable centre of any material chain here.
No structures
Nothing in this mod is found by exploring; all 120 items are made.
Modifiers versus smithing
The two upgrade systems are not alternatives. Apply Modifier works on items that accept modifiers, while the single smithing transform on 1.21.1 is a one-off conversion. With seven recipes between them, the sensible approach is to identify which of your items each applies to before spending material.
Smithing Template