Defiance is the only game in the series where both Raziel and Kain are playable: previous Soul Reaver installments focused on Raziel while the Blood Omen series focused on Kain. Unlike previous games where Raziel and Kain could acquire different types of weapons, in Defiance the only available weapon for either of them is their respective versions of the Soul Reaver – Kain possesses the material Reaver while Raziel possesses the Reaver’s spectral form. However, they do acquire Elemental versions of the Reaver, as Raziel did in the previous games. By killing enemies, Raziel and Kain learn new combat techniques, including uppercuts, mid-air slashes, and firing orbs of telekinetic energy. 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 Flame Emblem lets Kain use his telekinesis 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.
