It's time to duke it out in the Arena, doubtless the hardest section of the game. It's a series of rooms full of strong enemies, and your MP is drained to 0 while you're inside, so you can't rely on DSS.
Since there's no music in the Arena, I added my own:
Crimson Twilight (Overclocked Remix; from Castlevania Bloodlines)
In the Darkness of Time (Overclocked Remix; from Aria of Sorrow)
Dracula - The Belmont Revolution (from OC Remix's BadAss Boss Themes album)