As with practically all vampires - Nosgothic or otherwise - blood was necessary for Kain's survival. In Blood Omen, Blood Omen 2 and Defiance, his body constantly drained his blood reserves, just to stay 'alive'. Kain needed to feed regularly to sustain his unlife and, more importantly, to heal the wounds he received in battle.
Unlike most fictional vampires, Kain and Vorador could consume blood from a distance, telekinetically drawing it into their mouths from an enemy's body. In Blood Omen, Kain could also feed from Blood Fountains. In that first game, Kain had to be careful about which blood he drank. Although it wasn't a factor in the later games, blood originally came in four types, identifiable by its colour.
| Red Blood | "Normal" blood that Kain could obtain from humans and some creatures. This would replenish his health. |
|---|---|
| Green Blood | Poisonous blood. If Kain drank this, he would become poisoned and his body would need to consume blood far more rapidly to repair the damage it caused. He could be cured instantly with Anti-Toxin, but the poison effect would also wear off in time, if he had enough blood to wait it out. |
| Blue Blood | The blood of ghosts or spirits. If Kain drank this his magical energy reserves would increase, enabling him to cast his spells. |
| Black Blood | This would nullify the healing effect of the blood Kain already carried in his body (meaning it reduced the amount of blood that was in his blood vial). He had to avoid drinking it by accident. The Blood Fountains would flow with black blood after Kain had fed from them once. |