Braum is a tanky Champion who is very under-estimated, due to the fact that he is usually played as a support, which can lead to you gaining many kills. His Q scales with HP, meaning that if you build him with loads of HP, then you will gain more damage with your Q. By buying attack speed, you will be able to quickly stun them due to your passive which would help you secure loads of kills. Braum also has plenty of mobility as he can hop around with his W, which can be used as a gap closer or an escape tool. Additionally to this, Braum has his E which grants him bonus movement speed to help him get around easily.
Also he can support your carries buy tanking most of the damage and by also saving their lives now and then.

Pros

Tanky
Very under-estimated
Q damage scales with Total HP
Passive is easily proc-ed with additional attack speed
Great team fighter
Can easily support carries
Low mana costs

Cons

Slow wave clear
If behind can become worthless
Countered by high utility or mobility champions
Melee
Only one damaging ability (apart from ultimate)

The runes that I choose for Braum is mainly early game based (i.e. Flat AD, Flat HP). I do this to make him have a better lane presence to scare off enemies and make them think twice before going all in on you.
Mark of Attack Damage x 5 : This provides flat AD which would help you last hit easier.
Mark of Attack Speed x 4 : This provides extra attack speed so early engages will be slightly easier as you will proc your passive more often and more quicker.
Seal of Health x 9 : This provides you with the extra HP which will help you stay in lane longer and give you that needed early game presence.
Glyph of Scaling Magic Resist x 9 : This would give you that late game magic resist, as you will not be building a lot of it.
Quint of Attack Damage x 3 : This provides you with even more AD which makes your last hitting easier.

Offensive tree:

Provides additional AD
Provides much needed CDR, because we do not buy it in-game
Provides early game attack speed

Defensive tree:

Provides additional HP
Provides % HP
Provides sustain (HP regen)
Provides damage reduction

Utility:

Provides movement speed
Provides Mana regen
Provides CDR on summoner spells, meaning you can use flash and TP more often

Core items

is the most important item on Braum in my opinion, because of it's passive and stats which hugely increase his damage output and chasing potential.
is very important due to it's additional attack speed and magic resist, but mostly because of the extra magic damage it deal with each auto attack. This would make it very difficult for enemies to counter you as they would not completely nullify your damage output.
is very important becasue it nearly make it impossible for enemies to escape you because you will be moving at 400+ movement speed.
is very important because it causes the enemies to be endlessly slowed unless they have some sort of hard CC themselves. Stacked with attack speed, this item causes enemies to be constantly near you.

Offensive

is good on Braum because of the dueling potential and slow from its active.
is good because it removes one of your weaknesses by helping you waveclear much more easily. This item also provides life steal which can help in duels.
is quite strong on Braum because it reduces the enemies' armor meaning that you will do more damage. Additionally, it provides HP and CDR which are both good on Braum.

Defensive

is good because it provides you with a large boost in HP meaning that your Q will do loads more damage and you will survive longer in team-fights.
is good because it, like the Ravenous Hydra, improves your wave clear and provides you with armor.
is good because it gives you yet another slow and reduces the attack speed of enemies that hit you. Buy this if enemy attack speed based champs are fed or are too hard to kill.

Normal choices

is a very good summoner spell to have on Braum, because as you have very little or no sustain, having teleport could make sure that you miss out on very little CS and XP. Additionally, teleport can be used to gank other lanes, which would get you kills and/or assists.
is a very good summoner spell on Braum due to its ability to help you get that one last auto attack to secure a kill or to help you escape from sticky situations that could otherwise lead to your death.

Other options

is a good spell, but not very needed late game, because you will be able to chase many enemies with your basic abilities. At the late game, this spell can be used to split push or get objectives, when your teleport is on cooldown.
is a good spell only if you want to go very aggressive and can ensure that you will get a kill before you need to return to base. Additionally, this spell can be very helpful when dueling someone with high sustain like Dr. Mundo or Warwick.

During the early game, your goal is to farm as well as you can and to try and only use your abilities to escape and poke. Try not to engage on the enemy without your Trinity Force, unless if your jungler or mid-laner has come to gank. By the mid game, you should have taken their outer tower and possibly their inner one aswell. At this point, you can start to roam and help other lanes and secure objectives. However, DO NOT FOLLOW THIS EXACTLY, because there can be some instances where not following this would benefit your team more.

Your role in team-fights is to try and stun (and possibly kill) one of the enemy carries before they can do a lot of damage to your team. In addition to this, you should also protect your carries by blocking incoming damage with your shield and any projectiles with yourself. When a team-fight is about to start, you DO NOT initiate it, your job is to follow up by using your ultimate straight after the support has initiated the fight. This would mean that the enemy team would have to deal with two sets of hard CC. If played correctly, this could lead your team winning the team fight.

Thanks for reading my build guide on Top Lane Braum, this is my first League of Legends guide and I will hope to make more soon.

Please comment on anything you think about this guide, like how I can improve it or anything that needs changing due to patch updates.

Thanks :D