Brand Runes explained
There's one set of runes for Brand on patch
11.15
that is the clear favorite for LoL players and pros alike. The best Brand Runes on the position 
Adc are Sorcery as the primary path and
Domination as the secondary path with a pick rate of 80%. Besides runes you should take a look on Brand Build and if you are interested in pro matches take a look at Brand Probuilds. If you want to discuss
Brand then you should visit the champion subreddit.
Primary path on Brand
Sorcery empoweres abilities of Brand and increases the available champion resources. Most of high elo players – and our LoL pros in the the major regions – have agreed that
Arcane Comet is the best keystone rune to run on
Brand. This keystone rune adds more damage to your abilities and increases your power in the laning phase. This is usually followed up by taking
Manaflow Band,
Transcendence and
Scorch.
This is usually followed up by taking
Manaflow Band for additional mana and mana regenaration.
Transcendence for some more Ability Haste.
Scorch increases your control in the early game.
Secondary path on Brand
When it comes to your secondary path, most
Brand players prefer to go with
Domination.
Domination improves burst damage and assassination tools on Brand. On the
Domination path, the best runes for Brand are
Ravenous Hunter and
Cheap Shot.
Ravenous Hunter is the final rune of the
Domination path. This rune gives some survivability during short fights and damage trades during the laning phase. The additional health is nothing to scoff at and can mean the difference between winning or losing a battle.
Cheap Shot makes you deal more damage to enemies with impaired movement, which has great synergy with the setup of Brand.