It is impossible to use the anvil on something that would require more than 40 levels to enchant/repair, as to stop from vastly overpowered equipment being created.
How many operations did you use on those before trying to combine them? They clearly haven't been renamed, so each operation adds 2 to the prior work penalty, which adds together for both items (renaming sets it to 2 regardless of past or further work).
Also, Unbreaking and Thorns just aren't worth it on armor; even Unbreaking I on a tool is better than Unbreaking III on armor (2x the uses vs only 43%); Thorns doesn't do much damage compared to a good Sharpness V sword or Power V bow - plus you have to get hit for it to work; avoiding getting hit is what the sword/bow are for and it also reduces the effective durability when diamond armor already has relatively less durability compared to tools other than armor. Thorns is also EXTREMELY expensive, 24 levels for Thorns III, far beyond any other enchantment. Maybe useful in PvP but not plain survival.
I just use Protection IV on armor (only a chestplate and leggings, diamond-level armor) and that only adds 4 levels plus 1 for number of enchantments and 2 for prior work penalty for a base cost of just 7 - less than the cost of just Thorns I (8 + 1 + 2 = 11). For comparison, for the armor that you have, the base cost, ignoring the prior work penalty, would be 16 for Thorns II + 6 for Unbreaking III + 4 for Protection IV + 6 for three enchantments = 32 levels.
I also only use enchanted books on something that I really don't want to waste (mainly because I use mod armor/tools which makes diamond as easy to get as iron by comparison, also so expensive to repair that a Protection IV chestplate costs 20 levels to repair with one unit - so no putting on enchantments that don't really benefit), renaming it when I first make it or put the first enchantment on. Note also that using enchanted books is cheaper when combining because you already spent XP to enchant the book (unless you found it), also keeping in mind that each higher level needs more XP to get.
It's possible by using a thorns 2 book on one of them.
Yes it is possible but still will result in thorns II enchantment not thorns III so the only way is by combining two armors,even if,it will be too expensive.
OP the only way to get the required enchantment is to go to creative mod.
Fun fact: Thorns 3 is the rarest enchantment in Minecraft. It has a 1 in a 1000 chance
Fun fact 2: Thorns 3 only works on Golden armor.
Gamechap and Bertie made a video about it... might be slightly outdated, but I consider it legitimate.
*sigh* I don't know why nobody believes me. I checked all this before I even posted. Why don't you just pop into creative, make yourself a diamond chestplate, then go back to survival, use an anvil to put a thorns 2 book on it, and then add another? Like this;
Protection 4
Unbreaking 3
Thorns 3
Is this really not possible?
That's what I thought, but I looked it up to be sure and I kept reading 40. I guess you can't trust other people all that much.
I've never tried making skillbooks before. How hard would it be to get a Thorns 2 book?
Also, Unbreaking and Thorns just aren't worth it on armor; even Unbreaking I on a tool is better than Unbreaking III on armor (2x the uses vs only 43%); Thorns doesn't do much damage compared to a good Sharpness V sword or Power V bow - plus you have to get hit for it to work; avoiding getting hit is what the sword/bow are for and it also reduces the effective durability when diamond armor already has relatively less durability compared to tools other than armor. Thorns is also EXTREMELY expensive, 24 levels for Thorns III, far beyond any other enchantment. Maybe useful in PvP but not plain survival.
I just use Protection IV on armor (only a chestplate and leggings, diamond-level armor) and that only adds 4 levels plus 1 for number of enchantments and 2 for prior work penalty for a base cost of just 7 - less than the cost of just Thorns I (8 + 1 + 2 = 11). For comparison, for the armor that you have, the base cost, ignoring the prior work penalty, would be 16 for Thorns II + 6 for Unbreaking III + 4 for Protection IV + 6 for three enchantments = 32 levels.
I also only use enchanted books on something that I really don't want to waste (mainly because I use mod armor/tools which makes diamond as easy to get as iron by comparison, also so expensive to repair that a Protection IV chestplate costs 20 levels to repair with one unit - so no putting on enchantments that don't really benefit), renaming it when I first make it or put the first enchantment on. Note also that using enchanted books is cheaper when combining because you already spent XP to enchant the book (unless you found it), also keeping in mind that each higher level needs more XP to get.
TheMasterCaver's First World - possibly the most caved-out world in Minecraft history - includes world download.
TheMasterCaver's World - my own version of Minecraft largely based on my views of how the game should have evolved since 1.6.4.
Why do I still play in 1.6.4?
OP the only way to get the required enchantment is to go to creative mod.
Fun fact 2: Thorns 3 only works on Golden armor.
Gamechap and Bertie made a video about it... might be slightly outdated, but I consider it legitimate.