I got REALLY good with the Phoenix summon...or what ever one had rocks flying with some bird. It usually lasted long enough against dracula for me but it has been ages since I fought him :/

OH WAIT! Thats right. With the magician I got the BEST armor in the game. I went through that battle arena and got it since that one summon made it so smurfing easy. Nathan got MUCH stronger after that was put on. If I am not mistaken he could actually take a hit from dracula.