Dark Knights are the single most annoying point defenders in Seize. With their instant cast, reusable AoE, they can keep people from capping/uncapping for a good long while. A lot of DPS have AoE options as well, but they tend to go down quickly. Paladin and Warrior can last longer, but their AoE abilities pale in comparison. Dark Knight is the only class that can consistently harass cappers while staying alive long enough to protect the point.