Some techniques are shared by the two, others are unique to them, such as Kain's "Cadaverous Laceration". Raziel and Kain can also acquire various elemental powers that give them new abilities - the Conflict Emblem lets Kain use pyrokinesis to light torches while Raziel's Dark Reaver lets him turn invisible and pass certain obstacles and enemies without being noticed. When an enemy is weakened, Kain and Raziel can either absorb their blood/soul to replenish their health, or slay them with the Reaver, gradually filling up a meter that lets the Reaver unleash an area of effect spell to attack groups of enemies. Both Raziel and Kain can acquire various runes to increase their health and allow them to use their telekinetic powers more often. A menu system is used to display the character's combat experience, the runes they have collected and the various combos they have learned to execute.
The game begins with players controlling Kain, but at set intervals they will acquire control of Raziel and play as him for a time before switching back to Kain. Both possess similar powers, including climbing walls, gliding in mid-air and phasing through certain gates. However, both also have abilities exclusive to them: Kain can jump large gaps, transform into a swarm of bats and cannot swim, while Raziel swims and can shift into the spectral realm to bypass enemies and obstacles before finding an appropriate place to shift back into the material realm. Kain is also able to use his telekinesis to pick up enemies and either throw them into obstacles or pull them towards him, an ability Raziel lacks at first and must acquire during the course of the game. Enemies include Sarafan warrior-priests, Vampire hunters, Hylden-possessed corpses called Revenants, and various types of Demons.
Story
Defiance continues from where Soul Reaver 2 ended. In Soul Reaver 2, Kain saved Raziel's life by drawing the Soul Reaver from him - Raziel was meant to enter the blade and become its soul-devouring spectral half. This causes a time paradox that changes Nosgoth's history for the worse, and separates Kain and Raziel.
Kain's part of the game follows him seeking Moebius the Time Streamer, the guardian of time for answers to where Raziel is, how he has changed time, and later following a lead Moebius gives him to explore a Vampire citadel. During his quest, Kain finds and completes a broken talisman of Vampire construct known as the Balance Emblem. Kain discovers murals during his quest dictating an ancient war between the first races to inhabit Nosgoth, the Ancients and the Hylden. After sealing the Hylden in an alternate dimension using the Pillars of Nosgoth, the Hylden cursed the Ancients with bloodthirst, sterility and immortality, turning them into the first Vampires. Kain discovers from the murals that it was prophesied that both races would have a champion arise - a Vampire champion wielding the Soul Reaver, and a Hylden champion wielding a flaming sword. Because he possesses the material Soul Reaver depicted, Kain comes to believe he is the prophesied Vampire champion. The outcome of the battle between the two champions remains ambiguous.
Raziel's part of the game begins five hundred years later during the time of Blood Omen. Held captive by the Elder God, Raziel escapes his master and travels about Nosgoth hoping to find a way to avoid his fate of being imprisoned in the Soul Reaver. After being told by the Reaver's maker Vorador that only the deceased Janos Audron can give him the answers he seeks, Raziel travels to Avernus Cathedral to find Janos' heart and revive him. Raziel also finds murals of the Hylden and Ancients, showing the Ancients committing suicide in horror of their immortality. Raziel later discovers this is because the Ancients worshiped the Elder God, who had decreed all souls had to spin in a cycle of life and death known as the Wheel of Fate. Because they were immortal, their souls could not follow this doctrine and the Ancients became the bane of the entity they once revered. Raziel also finds murals of the two prophesied champions, and discovers that the Hylden champion and its flaming sword resemble him and the spectral Soul Reaver.
As Raziel enters Avernus Cathedral to search for Janos' heart, in the past Kain explores the Vampire citadel's deepest chambers and is contacted by the Elder God who tells him of what Raziel plans. Knowing what Janos' revival would cause (see Blood Omen 2), Kain accepts the Elder God's assistance and is sent to Raziel's time. In Avernus, after defeating the last of his brethren Turel, Raziel discovers Mortanius the Necromancer, who admits having helped Moebius lead the original crusade against the Vampires, and used Janos' heart to revive Kain as a Vampire to atone for his mistakes. Raziel returns to the cathedral's chapel moments after Kain arrives. Kain attempts to reason with Raziel and convince him not to revive Janos, but Raziel is under the influence of the Hylden and refuses to listen. The two battle, with Raziel defeating Kain and tearing Janos' heart from his chest. Kain, seemingly dying, is engulfed by a portal and vanishes. Raziel returns to Vorador's Mansion and uses the Heart of Darkness to revive Janos, who leads him to the Vampire citadel.
Raziel stumbles into a side chamber, the place where Kain had met the Elder God, and finds a forge designed to give the Soul Reaver its greatest power. However, the Elder God's tentacles emerge and attempt to bury the forge. Raziel fights off his master and has the Soul Reaver absorb the soul of Ariel, rendering the Reaver as pure of spirit. Ariel tells Raziel that this purified Soul Reaver is meant to be used by the Scion of Balance; however, evidence points towards Kain being the Scion of Balance, confusing Raziel as he returns to Janos.
At this time during the events of Blood Omen 1, Kain's past self refuses to sacrifice himself to restore the Pillars of Nosgoth, weakening the Ancients' seal enough for the Hylden Lord to possess Janos. The possessed Janos strikes down Raziel's physical body and causes him to shift to the spectral realm where he is again held captive in the Elder God's lair. Kain awakens, very much alive, trapped within the Demon Realm of the Hylden, and fights off their demons to return to Nosgoth. Entering the Vampire citadel, Kain finds Moebius reporting to the Elder God. Kain kills Moebius, causing his soul to shift to the Spectral Realm where Raziel impales him on the spectral Soul Reaver, revealing the Elder God's true form to him before devouring him. Undaunted, the Elder God informs him that Moebius no longer had any use for it, and it now intends to trap Kain and Raziel within the citadel for all time to prevent them from interfering with its plans any further. Raziel then considers all he has learned, and realizes that, through starting the war between the Ancients and the Hylden, and the war between humans and Vampires through Moebius, that the Elder God has been the cause of almost every hardship the land has faced in an attempt to keep its Wheel of Fate turning. Realizing what has to be done as his final act of free will, Raziel uses Moebius' corpse to manifest in the Material Realm and tricks Kain into stabbing him with the material Soul Reaver before the manifestation completes. Kain is horrified and attempts to remove the sword, but Raziel reaffirms both his free will and his loyalty to Kain, stopping him in the process. Raziel passes on the purified Soul Reaver into Kain to heal both Kain's corruption caused by Nupraptor's madness as well as the open wound in his chest from Janos' missing heart. It also allows Kain to see the Elder God but at the same time sacrifices Raziel to the Blood Reaver, making it the original Soul Reaver. Kain now has two versions of the Soul Reaver, uniting what had been torn asunder by Moebius and the Elder God's manipulations. This gives Kain the power to defeat the Elder God and the entity warns it cannot be killed and will return before being buried under the rubble of the collapsing Reaver forge, though Kain turns a deaf ear to its threats. The game ends with Kain looking out on the Pillars of Nosgoth his past self had just corrupted, silently thanking Raziel for giving him hope for the future.
