Lets see, if we have a custom spell slot icon now

Author: Fyreum

assets/minecraft/models/item/icons/spells/spellbook_icon_precisestab.json

@@ -0,0 +1,6 @@
+{
+  "parent": "minecraft:item/generated",
+  "textures": {
+    "layer0": "erethon:item/spell_slot_1"
+  }
+}