Just wanted to share these combinations of reagents to get tier 2 Int and Spell Damage on a neckpiece.
Use the 1st recipe below to get T2 Int. Then use the 2nd recipe to get T2 Spell Damage. This works because you can't double up on INT in the 2nd enchantment and will guarantee that you get Spell Damage.
You can use the same recipe to get T2 Spell Damage for any Mage Staff. As a bonus, I also added the recipe for T2 Durable.
T2 Int
Slot 1: Mandrake Root
Slot 2: Mandrake Root
Slot 3: Mandrake Root
Slot 4: Honeynail Mushroom
Slot 5: Honeynail Mushroom
T2 Spell Damage
Slot 1: Zombie Brain
Slot 2: Zombie Brain
Slot 3: Mandrake Root
Slot 4: Mandrake Root
Slot 5: Honeynail Mushrooms
T2 Durable
Slot1: Penny Bun Mushroom
Slot2: Dark Splinter
Slot3: Honeynal Mushrooms
Slot4: Spider Gland
Slot5: Wolf Teeth
edit: The same also works for Tier 2 Spell Damage on Mage Staffs
edit2: Had to clarify other details on how to get T2 Int and SD