Soma Cruz is the reincarnation of Dracula. He discovered this in 2035, and later was forced to reuse his powers in 2036. In the non-canon game, Resurrection, he succumbed to his powers after "Mina"'s (truly a doppelganger) death, and became Dracula. He is the main villain of the game.
Soma first appears as the sixth boss in the Throne Room. He has three default attacks. His first is a wave of fireballs, which, during the second half of the battle, track Julius' location. His second attack is Dark Inferno, in which he fires out three dark, exploding fireballs. His final default attack is a shockwave, which can paralyze Julius. At half his starting health, Soma shoots four dark infernos, his hellfire tracks Julius, he fires two shockwaves in succession, and he can now shoot a bolt of lightning. His theme is Dance of Illusions, and he has 3333 HP. After his defeat, he releases Hammer, who reveals the location of the others.
Soma later appears as the eleventh boss inside the Chaotic Realm. His new four attacks are summoning thunder from over the arena, throwing 5 ice spikes in a spreading pattern agaisn't Julius, summoning a pillar of fire which races through the ground, and doing a great slash with a giant dark Claymore. He'll also try to punch you if you stay too close to him. At half his starting health, he'll summon a meteor storm which will last through the rest of the fight, until his defeat. His theme is Dance of Illusions, except it's a remastered version with more instruments. He has 6666 HP. Without any dark energy for Castlevania to sustain itself, the Chaotic Realm collapeses, along with Soma.
Even though Castlevania disappeared, Soma made a last ditch effort to escape into Mt.Fuji, where he tried to regain his powers. When you reach the peak of Mt.Fuji, the battle starts. He is the twelfth boss and final boss. Soma has two phases in this battle. In the first one, he'll throw fireballs in all 8 directions around him, ocasionally throwing some dark infernos which move much slower, but explode upon contact with solid surfaces, the fireballs don't. He will teleport at every few moments around the room. He will rarely execute a great slash with a giant dark Claymore every now and then.. When he reaches 0 HP, his HP will be completely restored, and the second phase will begin. He'll throw ricocheting fireballs around the arena, doing horizontal and vertical slashes with his bat-like wings. He will also do his great slash with a giant dark Claymore, except now he does it three times in a row, first vertically, then horizontally, then vertically again. At 1/3 his starting health, he'll cover himself in flames and tackle around the arena horizontally while throwing more ricocheting fireballs. The first phase theme is Dance of Illusions, except with an orchestra-like feel. His second phase theme is Banquet of Madness. After his defeat, Mt.Fuji collapses along with Soma's soul.