I'm looking for an HP fanfic I read a long time ago, probably originally published on FanFiction.net somewhere between 2005–2008 (definitely before 2012). It may have been deleted from FFN since — I haven't been able to find it there. It read it around the period that it was published/completed, so I may be misnumbering some details or mixing some up with another similar story.

Details I'm certain of:

The climax has a solo assault of Voldemort's black castle fortress by Harry. I think the fortress was hidden by wards/fidelius and think it might have been suspended in the sky, but I could be misremembering that last part.

Set during Harry's 6th or 7th year.

Independent Harry - he goes off on his own path rather than staying under the Order/Dumbledore's wing.

Harry develops a dueling style built around extremely fast/short-range apparition.

Details that I may be misremembering:

Harry's solo final battle with Voldemort mentioned above ends with Harry using some kind of final resort self destruction spell, the explosion from this kills Voldemort and also destroys his fortress.

Early in the story, Harry is given or recommended an advanced battle magic book — I want to say by Moody, Dumbledore, or Sirius (not 100% sure which). There's a scene of Harry reading this book (or possibly a letter) under a tree.

Harry undergoes training/studying during the summer/early part or the story to

I think he also learns to dual-cast with two wands at once, but I'm not confident about this detail.

I know this is a fairly thin/hazy set of details, but if anything rings a bell I'd love to track it down again. Thanks in advance!

 

Did the final fight read more like a Naruto fic than a HP fic?