Brand

Support

Middle

Blaze a Trail

Massive damage on slowed targets.

Sorcery

Empowered abilities and resource manipulation

Arcane Comet

Hitting a champion with spells hurls a comet that deals adaptive damage at them. Landing more spells reduces Arcane Comet's cooldown.
Manaflow Band

Hitting enemy champions with a spell grants maximum mana.

After reaching 250 mana, Manaflow Band restores 1% of your missing mana every 5 seconds.
Celerity

Gain 3% extra MS. Gain extra AP or AD, based on your bonus MS, Adaptive.
Scorch

Your first ability hit every 20s burns champions.

Inspiration

+20 Ability Power or +12 Attack Damage, Adaptive

Magical Footwear

You get free boots at 10 min. but you cannot buy boots before then. These boots give additional MS. For each takedown you acquire the boots 30s sooner.
Cosmic Insight

+5% CDR
+5% Max CDR
+5% Summoner Spell CDR
+5% Item CDR

WhyArcane Comet

Brand is a champion that can quite regularly land Comet once you have Rylai's.

The DoT from his passive also helps dramatically reduce the cooldown of Comet while they are burning.

WhyManaflow Band

As a high damage support, your job is to provide lane pressure with frequent harass from ability spam. Manaflow provides you the mana sustain to keep the pressure up.

Pay attention to the cooldown and try to utilize the mana refund on [W], your highest costing ability.

WhyCelerity

Celerity's Bonus Movement Speed is great for allowing you to skirt the edges of your ability ranges for lane poke and harass.

WhyScorch

Scorch is a rune that really plays up on heavy lane aggresison and dies off over the course of the game.

If you expect to game to go to late you can forgo that early damage for scaling with Gathering Storm instead.

WhyMagical Footwear

Magical Footwear allows you to take advantage of your aggressive laning phase damage by snowballing any kills/assists you pick up into a father damage itemization.

WhyCosmic Insight

Cosmic Insight's well-rounded utility provides you more damage in the form of CDR and kill potential with Summoner CDR.