Hi guys, I'm running Frozen Sick with my little brother, and he is playing as a wood elf fey wanderer. Since he is on his own, he is level 3. We have played just a little bit, he has gone to croaker cave, antique store, dead dwarfs house and diseased dwarfs house. His build is as follows: wood elf fey wanderer, ability scores: 16 dex and wisdom, 13 con, 12 charisma, 10 intelligence and 8 strength. Equipment wise, he has a longbow, made himself studded leather armour, boots of the winterlands and a flame tongue rapier. I gave him boots as it is useful, and it is only uncommon. But the flame tongue rapier is causing trouble. He keeps on one or two shotting people, and it is just because of it. I couldn't find any bows that were rare or less, other than +1 and stuff (his character is about the longbow). However, he did come down from 25 to 12 hp in a fight, and it was in the antique shop. I think I might add more powerful enemies, so that he can't one or two shot them, and they can deal ok damage to them. I have told him that I might remove it, or he loses it, and he's ok, but I would rather not. I think that the easiest option is to make the villains slightly more powerful, so he can still have fun. I would like to point out, we did this all today, because he was bored, so I made the character, printed it and the adventure off then we played. Fun come first, and we are both having fun, even when he does just kill people. However, he does like roleplay, and does interact with NPC's (he made the studded leather with a bandit, who wasn't having fun as a bandit, and so when his 'friends' died, he was just happy. So he's good at most aspects of the game. 

I woulnd't worry about him 1 shotting people since it's a one man party.  Maybe roll the enemy HP instead of using average.  Increasing the variance will make big hits less effective against them.  For example, you could have three enemies with hp average 10.  If he hits for 12, 11, 14 and you rolled their hp as 14, 8, 9 then he only kills 2 of them in three attacks instead of killing all of them in 3 hits.

So, unfortunately, other than the Oathbow there really are not any unique bows. Theros released a really cool shortbow but its legendary so I would stay away from that. You can consider looking at other magical weapons to inspire you to just homebrew him something fun... but BE CAREFUL. if he's decimating with a flame tongue, even going slightly overboard will make things worse. Though you can consider giving this bow a magical quiver of arrows like hawkeye. 1 per use per short or long rest. like 1 fire arrow, 1 trap arrow, 1 summon beast arrow, etc. look through the druid/ranger spells for inspiration as well.

Not sure, if you heard the term 'action economy' but since D&D is turn based, numbers (or numbers of attacks) is a severe advantage. Which is why a party of 5 can fairly easily take down a monster double their CR. Before the monster gets a turn, 5 or more attacks will be taken against them (it's why legendary actions are a thing) so that being said, your brother should actually be overwhelmed. You should DEFINITELY use numbers against him.

That being said, check out the blog I'm going to link at the bottom. This guy reads through stat blocks and lore to formalize actual tactics for each monster (that he had a chance to get to). As opposed to just "Everyone attack everyone" he goes through which would think about tactics, which would attack blindly, which would stay to the death and even which would run away. You may not need to get too complex with your brother but with just one player, rinse and repeat it can get boring if you don't add some life to it.

In the essential guide, they introduced hirelings or sidekicks. a quick easy NPC that players can control and even level up. There are the 3 basic archtypes, fighter, spell caster and rogue. Look into them if your brother needs support.

http://themonstersknow.com/

Nice. I have tried to roleplay the NPC's so that they would be natural, so bandits are pack tactics, the giant frogs don't care, but might not attack if others are there etc. He won't level up (if he does, it will be to 4, but that's a rare opportunity), and so he will stay like this. Most times he has barely been shotting them, only doing 15 damage. Although he has got a crit.... He was mean and did around 30 damage 

how is he doing 15 damage? d8(longbow)+d6(hunter's mar)+3 or 4(dex mod at lv3) is an average of 10 or 11... though it can be like 17 or 18 on max damage but how often does he roll max on both the d8 and d6?

Also RAW, criticals let you roll ALL the damage dice twice, and modifiers are left as is. So lets say he rolled 5(longbow)+4(HM)+4(Dex) instead of just *2 to 22 he would instead roll 2d8+2d6+4. My opinion makes it more fun having the entire table filled with dice

Quote from Noxx89 >>

how is he doing 15 damage? d8(longbow)+d6(hunter's mar)+3 or 4(dex mod at lv3) is an average of 10 or 11... though it can be like 17 or 18 on max damage but how often does he roll max on both the d8 and d6?

Also RAW, criticals let you roll ALL the damage dice twice, and modifiers are left as is. So lets say he rolled 5(longbow)+4(HM)+4(Dex) instead of just *2 to 22 he would instead roll 2d8+2d6+4. My opinion makes it more fun having the entire table filled with dice

 OP said he gave the ranger a flame tongue rapier which does an extra 3d6 fire damage.

Ah, I thought he was doing that with a bow... So OP needs to swarm the ranger.... Tucker's kobold style. Not enough to drive him insane but enough to badger and cause some trouble