It's an alright build. I don't really like the lack of spellvamp and mana regen, especially with how quickly he burns through his mana. Also I think you should go for magic pen marks, instead of AP runes. I can see them helping end-game, but even then magic pen would help LOTS.

Try adding an AA's or anything like that.

You do have a point there about MPen, I will be missing it early game, but in the late the AP will prevail. So it's a toss-up, I guess just preference? The item build I showed only has the 4 core items of the build, the rest is totally situational and preference ^_^. You could definitely get a Rylai's with this build it's fantastic at making your Q,W and R hit more easily! Not sure about ROA end game, because you really wanna get the bonus stats from time and at that point the game might be ending soon.
I don't believe in rushing it either, I feel there are other better items out there.

Thanks!

Thank you! And your comment is noted!

Eh, I just noticed all your trollvotes.
Just because of those i'll change my vote to +1, but my points still stand :)

You DO need the MPen from runes, especially early-game before you get your boots. Also, you want as much MPen as is possible, as it adds to the damage of your passive, Blaze.
But your main problem is the lack of damage lategame. If you're playing this build, after around 40minutes you will become almost useless. You don't have enough AP to deal major damage even against squishies, and against tanks it will be even worse. Without Rylai's or Rod of Ages you'll be a walking pile of (flaming!) gold.

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Spell vamp isn't necessary on all casters, sure it gives you some health back, but it's not like the fights are going to be that long. Also, all teams have CC, CC that banshee's would block. ALSO, if this is even close to a smart enemy team, they'll have a balance, therefore you might want a bit of MR/Armor.
I almost always get mr because it's something to make your catalyst into (I don't think RoA is very good)
And your base MR will not get higher as you lvl, while your armor will, so once you get BV they should be close to the same.

Bad stuff, no spell vamp and Banshee is usefull only versus an AP team.

thanks for the guide

Effective! A build that worked very well for me and your description+tips are very useful!
+1

Good luck getting to the top of the Brand builds!