Hey Summoners.
This is the first guide I have written, so bear with me as I tend to ramble. It is very rough and has no pretty pictures, something I plan to work on, but i felt it was important to get a reasonably comprehensive guide out NOW. So please, bear with me hopefully i didn't run my mouth too much, and you like my build. Without further ado, lets get started.

Before we get started there are a few skills that are essential to being sucessful with Brand:
1. Being able to hit skillshots consistently:
I cannot stress this enough. if you CANNOT consistently and swiftly execute and convert on your skill shots you will FAIL as brand. His entire game play synergizes around landing that stun. it is what procs that second blaze and sets the stun for the 25% bonus damage from your pillars of flame.
2. Comboing:
Rapidly casting skills accurately quickly and IN ORDER. If you get nervous and end up mashing your skills, you will have a very hard time with brand. Staying calm and quickly exectuing your combo will end up in devastating damage, and will instill fear into your enemies.
3. Judgement:
Brand has no escape skill. He is not remarkably fast. He is not like Anivia, Veigar, Ryze or Heimer, who have 1 click stuns(yes Anivia and Heimer's are skill shots but you have to hit 2 skills WHILE running away to set the stun for Brand). Although I encorporate flash into this build, it should be a move of last resort. So engaging with Brand must be considered carefully and battle awareness is a must.

PROS

One of the biggest nuke combos in game

Solid early, mid, and late game damage output(rare for caster)
Great nuker
Great farmer from midgame on
High skill cap
Stun
Huge Teamfight potential for ult

CONS

No escape move
Skill shot reliant
Takes time to master
Squishy

Passive Blaze - Brand's spells light his targets ablaze, dealing 2% of their maximum Health in magic damage per second for 4 seconds
What sets Brand apart from the rest. This passive allows him to have a decent early game damage out put, especially while magic resistances are low.

Sear - Brand launches a ball of fire forward that deals magic damage. If the target is ablaze, Sear will stun the target for 2 seconds.
Great poke. Great effect. Low mana cost. Low cool down.
This ability is the linchpin of brands potential. Whether or not you can effectively use this ability will determine your success as Brand.

Pillar of Flame - After a short delay, Brand creates a pillar of flame at a target area, dealing magic damage to enemy units with the area. Units that are ablaze take an additional 25% damage.
Great for farming in combination with conflagration. When comboed properly, really turns up the heat on your damage output.

Conflagration - Brand conjures a powerful blast at his target, dealing magic damage to them. If the target is ablaze, Conflagration spreads to nearby enemies.
Honestly nothing special with this skill. Target-able so can harass with it in minion traffic. sets up your combo. Farms well with pillars.

Pyroclasm - Brand unleashes a devastating torrent of fire, dealing magic damage each time it bounces. If a target is ablaze, Pyroclasm's missile speed increases.
A very fun ult. Can be unpredictable but can devastate enemies if they stay close together.

Quints: MPen.

I cannot stress this ENOUGH; penetration runes are the strongest choice for increased damage output. Some people choose AP and that is a mistake. You may do a tiny bit more damage to minions, but not to champs at any level. An example.
AP quints vs Mpen quints 200 item AP (ignoring other penetration just from quints).
Enemy with 50MR will suffer 253.166 damage from lvl 5 sear with AP quints.
Enemy with 50MR will suffer 256.366 from lvl 5 sear with Mpen Quints.
So it may be only 3 damage but its more and that is with Brand's best scaling skill.
A convincing argument for penetration in all cases if you want more damage.

Marks: MAGIC PEN.

See above. Nuf said.

Seals: Scaling MP/5.

As Brand levels up his skills become more and more mana hungry. Building morello's evil tome early helps but this helps keep you topped off.

Glyphs:

Scaling CDR. Brand is a burst damage character. If you can get 40% cdr (with this build you top out at 37.1) you can almost proc your sear on its own!! Being able to cast his spells quickly while the enemy is still ablaze is CRUCIAL.

Pretty standard 9/0/21
Recently I came to realization (actually someone in their guide, I'm sorry I can't remember who actually) that taking ANY (unless you have nothing else to put them in) points in perseverance is pointless for a caster. There is no significant hp regen and even if you had 100 mp/5 it would only go up by 4. 10% reduced death time is infinitely more useful when the 6 seconds saved late game mean the difference between losing an inhib and losing the game. As well expanded mind is pretty pointless too because it only increases mana by 5% of YOUR BASE mana. take the extra gold, take the extended buff duration, take the enhanced flash.

I prefer to take flash and ignite.
Flash fills the gap where brand is severely lacking: escape. Often times I use flash to get up over walls and terrain rather than to just blink away unless it is from a gank. If you are less comfortable with that take ghost; just make sure to change your masteries. The duration should allow you to get some separation and hit the stun or just plain get away.

I like ignite as my second skill to take out that last bit of damage and keep those pesky healers and Mundo from healing up in between your viscous combo.

Ghost and Flash work well if you are worried about getting caught out often.

Clarity would only be useful very early game and then even then not really.
You are building that rylais quick so exhaust isn't necessary, and you shouldn't be in the thick of things so cleanse isn't a good option either

I rush Morellos first because you can enter the mid game with your CDs as low as they are going to get. Earlier in the game when chracters are not as farmed and have worse items, being able to hit a stun often means a death. And if it doesnt I cant count the times where they are running away with 100 health and my sear comes off CD and I pick them off for a kill. Brand is a mage, his attack damage is low. You arent going to get more damage autoattacking them becuase your skills procced rylais if you build that first. Get your Cdr. Get your skills off quickly and often. Get your kills.

I Cannot stress more getting rylai's after you get your boots. People love rabbadons. I love it too but being able to get that slow from conflagration makes hitting the sear that much easier. You will have a lot of killing opportunities in between the 6000 gold from building rabbadons to finishing rylais. And getting rylais first will make getting rabbadon's deathcap that much easier.

I Choose Banshees veil because he is so susceptible to CC and he only gets into trouble if he gets tagged with a disable and then the enemies get close.

I like WoTA as my last items for 2 reasons. 1: Brand doesn't have a heal and his regen is ****. you don't want to have to blue pill after every team fight. You want to be able to clear minions and push. Will of the ancients lets you do just that. 2: its aura. As a mage you shouldn't die much. giving the rest of your team 30 AP and 25% spellvamp helps immensely in team fights and gives you a greater presence in the Late late games when tanks and enemies have caught up to you with MR. Of course These are all situational. If their tank is giving you trouble take void staff or abyssal scepter. If you keep getting caught by that lone spell get the banshees first.

My only advice would be to build Morello's boots and Rylais Always and Always First.

Most Brand guides take conflagration as their first skill. That is ALL WRONG. It wastes mana does less damage and has no ultity early except for harassing. And even if you do you will be risking putting your squishy butt close your enemies most likely pulling minion aggro and wating time when you should be farming. TAKE SEAR. does the most damage costs the least mana. lets you extend your sphere of influence. Also one of the most underused and little known fact about most skill shots. THEY MAKE A SECONDARY SOUND IF THEY HIT SOMEONE. So now you can just shoot a sear into the bushes at the beginning of the game and avoid giving away an embarrassing first blood. As well, because you need a clear line of sight you aren't going to abuse it early and spend the early lane phase consistently low on mana. If its too hard for you to hit with it pick a new character. I also find it nice that I can start with it so I can re familiarize myself with its timing, so later when I have my levels I don't whiff.

After taking sear at 1 its pretty straightforward. Get conflgration to 2 and with Pillars you should be able to clear the 3 ranged minions. Alternate sear and pillars, and take your ult whenever you can.

This is short now and may be expanded but brands combo is pretty straightforward.
For single enounters and ganks, hit with conflagration, tag with sear then set the pillars right underneath them. This NON-ULT combo does Massive damage and will be your bread and butter.

Often times people like to finish people with their ults. While this is a good strategy for Brand it can also be useful to open with it once you know a team fight has started. This is because it will kit multiple targets and you can use your conflagration to spread the blaze to make sure all the enemies are ablaze to get your 25% bonus of pillars. Other than that use it when you can get it to bounce of either minions or enemies to get multiple hits on the same target.
A good comparison is annie, often regarded as one of the strongest nuke mages with her stun.
you have that same capability (No AOE but your ult combo almost does ALOT more than her ult combo. don't believe me? look)
just looking at true damage here not pen.
Both have 300 ap
Annie Tibbers --> Disentigrate --> Incinerate
(450+300*.7) + (260 + 300*.6) + 325 + (300*.6)
=

1605

1205 per person in range
Brand Pyroclasm --> sear --> conflagration --> Pillars
(350 + 300*.5) + (240 + 300*.65) + (210 + 300*.55) + ((260+ 300*.6)*1.25)
=

1860!!!

1525 per person(excluding multiple hits from ult)
This power does not go unnotice as your melt the ENTIRE enemy team's hp in a blink of the eye.

This is my first build and obviously very rough and not flashy. If you have suggestions or tips please let me know and tell me what you think of the guide.
I hope this was helpful, and I would like to see you soon on the fields of justices burning your foes to the ground.

Thanks for reading and vote if you like it.