I have a player in my campaign that is hitting for +16 to hit. I'm not exaggerating. 

He is a minotaur fighter with 20 STR, holding a +5 to hit magical greatsword he had made for him. He hired three master dwarven smiths and a legendary enchanter to do it. 

At level 8, there should be no way for him to do that. 

Is it even possible?!

Help! He is breaking me, the DM. There is literally NOTHING he cannot hit, and if I tailor any monsters to combat this, they will destroy the rest of the party.

Note: there were two instances where he nearly fell to inferior opponents: a green hag that put him.in a magical headlock and AOE nearly one hit KO. The other was when a T-rex got him grappled in its jaws and nearly shook him to death. Only two times. He got the sword at level 7.

Quote from Hikerboy7 >>

I have a player in my campaign that is hitting for +16 to hit. I'm not exaggerating. 

He is a minotaur fighter with 20 STR, holding a +5 to hit magical greatsword he had made for him. He hired three master dwarven smiths and a legendary enchanter to do it. 

At level 8, there should be no way for him to do that. 

Is it even possible?!

Help! He is breaking me, the DM. There is literally NOTHING he cannot hit, and if I tailor any monsters to combat this, they will destroy the rest of the party.

Note: there were two instances where he nearly fell to inferior opponents: a green hag that put him.in a magical headlock and AOE nearly one hit KO. The other was when a T-rex got him grappled in its jaws and nearly shook him to death. Only two times. He got the sword at level 7.

Why did the DM give him the sword? A player can't just say that he has a sword that goes beyond the standard weapon enchantment range.

How does he get +16 to hit? With 20(+5) Strength and a +5 greatsword and a proficiency bonus of +3 at level 8 he would only get +13, but I agree that that is way too overpowered.

I understand how he could have that high of Strength, but the sword is the real problem. A +3 weapon is classified as Very Rare, and so a +4 would be a Legendary, and a +5 would be even greater (though not as good as an Artifact). If a PC has a magic item that powerful at 7th or 8th level it will probably break the game, and this problem is probably why the rules do not have weapons higher than +3. Even if you could get such a powerful item it would take (in my opinion) a few hundred thousand gp at least, which is not something low-level adventurers usually have.

My advice to fix this would be a "disturbance in the Force" method. Great power attracts great enemies, and he may be forced to not show his weapon as much. perhaps he could put it into a secret vault until he is powerful enough to fight the enemies it attracts. If worst comes to worst you can just talk to the player about the problems his sword is making.

Hope this helps.

Again, a player can't just say he has the sword. Take it away from him or have an assassin murder him in his sleep. I would recommend the latter.

The OP says the PC hired 3 master dwarven smiths and a legendary enchanter to make it. What I do not understand is how he got that much money.

Quote from Hikerboy7 >>

I have a player in my campaign that is hitting for +16 to hit. I'm not exaggerating. 

He is a minotaur fighter with 20 STR, holding a +5 to hit magical greatsword he had made for him. He hired three master dwarven smiths and a legendary enchanter to do it. 

At level 8, there should be no way for him to do that. 

Is it even possible?!

Help! He is breaking me, the DM. There is literally NOTHING he cannot hit, and if I tailor any monsters to combat this, they will destroy the rest of the party.

Note: there were two instances where he nearly fell to inferior opponents: a green hag that put him.in a magical headlock and AOE nearly one hit KO. The other was when a T-rex got him grappled in its jaws and nearly shook him to death. Only two times. He got the sword at level 7.

He didn't "get" the sword.  You said he made the sword through employee the Dwarf master forgers etc.  Did this happen in your campaign?  If so, the answer to "why is this" is you allowed it to happen (and I just don't understand how a level 7 character managed the cost of that creation).  If this character is being brought into your campaign it's your perogative to say "I'm sorry, this character is far too overpowered for the play we're doing here. I'd be happy to work with you to rework this character into something that works with the rest of the party and the game world, but I can't accept this character into the game world."  

Use the dragon solution... 

Have a ancient dragon eat him... 

 Then have the dragon conclude that the rest of the party now owe him... Instant plot hook and new adventure... also party patron. =D 

Problem solved. 

I think the DMG has advice for you? "ANNOUNCE THAT TIAMAT SWOOPS FROM THE SKY AND ATTACKS."

An enchantment falls over the party as they rest, and the magic item gnomes come in and make off with the sword.  

1. collect powerful magic. 

2. ???

3. profit!

or

the dwarven smiths and the enchanter show up and the player shorted them 15.5 millions gold and they are repo-ing the sword until he can pay. 

Quote from ThriKreenWarrior >>

An enchantment falls over the party as they rest, and the magic item gnomes come in and make off with the sword.  

1. collect powerful magic. 

2. ???

3. profit!

 

or

 

the dwarven smiths and the enchanter show up and the player shorted them 15.5 millions gold and they are repo-ing the sword until he can pay. 

 15.5 million's a bit little, don't you think?

Quote from kooma_ruma >>

The OP says the PC hired 3 master dwarven smiths and a legendary enchanter to make it. What I do not understand is how he got that much money.

 Technically, any weapon of +4 or greater is god-tier. In my world, no weapon can ever grant any bonus higher than +3, and almost no one has even +3 weapons.

Quote from Halfastbracegirdle >>

Quote from ThriKreenWarrior >>

An enchantment falls over the party as they rest, and the magic item gnomes come in and make off with the sword.  

1. collect powerful magic. 

2. ???

3. profit!

 

or

 

the dwarven smiths and the enchanter show up and the player shorted them 15.5 millions gold and they are repo-ing the sword until he can pay. 

 15.5 billion's a bit little, don't you think?

You should have a conversation with the player. Explain how, as a new DM (I assume), you have been mistaken in allowing such a powerful artifact. You are going to request that he allow you to retcon the sword into something more reasonable. Warn him that you cannot continue to allow this character, as it is game-breaking, so he can either agree to a more sane weapon, such as a +2 sword, or else you will have to enforce some in-game mechanism of blunting it, which he will like far less.

If he refuses, the smiths have been bragging about this sword, and now every swordsman far and wide wants it for him or herself. And thieves want it for the value. Introduce an escalating series of enemies that WANT THAT SWORD and keep going until someone gets it and takes it away from him. And don't give it back. Ever.

My rule of thumb when a player wanted to do something overpowered - if a PC can do it, so can an enemy.  So if just any old 8th level character or equivalent monster can get enough money to buy a sword like that - then you better believe that the bad guys will have it too.  

I let the party vote.  If the party wants to run across lots of enemies who have +13 (or whatever) to hit attacking them - then that's their choice.  But it will be no fun for the other PCs.  Usually, they vote the right choice.  If not, they had their chance.

As an alternative, as BioWizard stated above - there is a price on the party's head and everyone wants the sword.  There are lots of ways to disarm a character.  Or use spells with will saves or such.  It could be as simple as a couple of spellcasters using "command" every round ordering him to drop it and a rogue holding an action to scoop up the dropped sword.  It could be as simple as a drugged drink at a bar.  Or the party could come into a town where it is not acceptable for adventurers to walk around bristling with weapons.  It could be a warlock with abilities to boost the range on his eldritch blast, or a couple of wizards on horseback who keep pelting him mercilessly with magic missiles and the fleeing.

The smiths made a powerful weapon but didn't say how long the enchantment would last. After every encounter, the weapon loses a +1. So after 5 fight, it's just a fancy looking sword.

Sidenote: Don't let this kind of thing in your game. It's YOUR game. 

I still suggest you kill him. Tiamat works.

My rule of thumb when a player wanted to do something overpowered - if a PC can do it, so can an enemy.  So if just any old 8th level character or equivalent monster can get enough money to buy a sword like that - then you better believe that the bad guys will have it too.  

I let the party vote.  If the party wants to run across lots of enemies who have +13 (or whatever) to hit attacking them - then that's their choice.  But it will be no fun for the other PCs.  Usually, they vote the right choice.  If not, they had their chance.

Yup.

If the PCs can do it so can the monsters. If 8th level PCs have +5 weapons, then high-CR monsters are going to have +7, +9, etc. This is going to get non-fun, VERY quickly, for the rest of the party, if not for the offending player.

And oh crap, that monster not only has a +5 weapon and the same +16 to hit as our PC, but he has multi-attack AND can attack with it as a legendary action.... 3 legendary attacks with it plus 3 multi-attack attacks = 6 attacks per round at +16. ONE fight like this and they will beg you to take the sword away.

Helm wears +5 everbright full plate armor. Unless he is on that level and fighting against gods, there is no place for someone to have a weapon or armor like that.