Mark for Blood by pressing {hotkey:SOCIAL_WHEEL} and scrolling through the wheel options. Once Bloodmarked, you can attack other players.
Bloodmark can be removed by using an Altar of Cleansing found in town.
Seeds of Hatred can be obtained from monsters, events, and chests. Dropped seeds can be picked up by anyone. Seeds are dropped upon death and completely purged when leaving the PvP area.
Turn Seeds of Hatred into permanent Red Dust by performing Purification Rituals. Red Dust is used at various vendors within town.
Defeat players while Bloodmarked to become Hatred's Chosen. While Hatred's Chosen, your position is revealed to all players in the area and you cannot perform rituals at Altars of Extraction. Survive to receive powerful rewards. Hatred's Chosen is forfeited when entering town or leaving the area.