Discipline Healing DK Tank
Death Knights are a plate-weaving class to earn World of Warcraft Gold, giving them a high migration which decreases the amount of physical damage they take in turn. Additionally Death Knights have several talents like Frost Aura and Anti-Magic zone that give them added resistance to spell damage. However, Death Knights can not equip shields and block incoming damage, unlike Warriors and Paladins but more akin to Feral Druids. Therefore they are avoidance tanks. That is to say, Death Knights can dodge, parry and avoid, rather than relying on being able to mitigate incoming damage.
Like Feral Druids, Death Knights do not utilize rage and mana like protection Paladins as well for their abilities. They use runes, generated and expended through their different abilities. Though a Death Knight that mismanages her or his cool-downs could run out of runic power, one can't go OOM or be "rage-starved" like other tank classes. In particular, the latter is important which means that a Death Knight needn't take damage in order to generate rage and subsequently threat.
As mitigation tank, the part of the preference healers have for protection Warriors is that the damage they take is consistent over the course of a fight. Healing is "easier" because of this. Avoidance tanks are often accused of being "squishy," because while they may spend much of the time at full health, when a hit does land, it lands hard. While all tanks do require healers to react to the circumstances of incoming damage, avoidance tanks benefit f Aion proactive, rather than solely reactive healing.