So I just finished up a basic bots custom game (since I know people will be trying him in Co-op Intermediate), and so far, I like the idea behind him. He's a bit of a mix between Malzahar (HP% damage) and Annie (though instead of granting stun to every spell after 5, Brand gets a special effect when targets are ablaze). Anyways, here's an overview:
Blaze (Passive): Brand's spells light his targets ablaze, dealing 2% of their maximum Health in magic damage per second for 4 seconds.
This is pretty nice. Percentage health damage is deadly. It's what makes Malzahar's Null Zone, and Mundo's Infected Cleaver pretty damn powerful. This allows you to either stack it with Ignite, or replace Ignite with something like Clarity (because he does have mana problems early game).
Sear: Brand launches a ball of fire forward that deals magic damage. If the target is ablaze, the target will be stunned for 2 seconds.
I'll be frank, this skill is pretty bad. Of course, I am speaking in terms of usability. It's currently suffering the same problem Lee Sin's Sonic Wave has: it's too slow. The animation delay for it is also pretty funky. It's not like Lux's Light Binding or Morgana's Dark Binding, where it's easy to aim because of the quick animation. With that said, this is going for a LV1 till others are maxed.
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.
This is where the majority of your nuke comes from. Properly landing this on mobile and stunned targets is key. It's also AOE, which is a big plus in teamfights. Also, this has the longest range out of all your spells. Max this out first.
Conflagration: Brand conjures a powerful blast at his target, dealing magic damage to them. If the target is ablaze, the conflagration spreads to nearby enemies.
This is your opener to your combos, always. It's got pretty decent damage, but the Blaze bonus isn't really that great. Max this second.
Pyroclasm (Ultimate): Brand unleashes a devastating torrent of fire, dealing damage each time it bounces. If a target is ablaze, Pyroclasm's missile speed increases.
This is one of the harder ultimates to land properly for full potential. It will, however, be easier to do so when you are attacking the enemy Nexus, because it WILL bounce on minions. Max out whenever possible.
Greater Mark of Insight - MPen
Greater Glyph of Replenishment - MR/5
Greater Seal of Focus - CDR
Greater Quintessence of Fortitude - Flat Health
Greater Quintessence of Potency - AP
Core: Rylai's Crystal Scepter, Archangel Staff, Void Staff
Plausible Items: Rod of Ages, Mejai's Soulstealer, Morello's Evil Tome, Zhonya's Hourglass, Rabadon's Deathcap