Horn of Winter

Horn of Winter is a group buff that Death Knights can cast, increasing strength and agility. The ability also generates a small amount of runic power when used. The buff should be kept up at all times, as the attack power gained from the strength and the critical strike chance gained from the agility will increase your damage done significantly. As a tank, the extra strength will increase your damage (and therefore threat), as well as your chance to parry through Forceful Deflection, while the agility will boost your armor and chance to dodge.

Tips and tactics

 * Horn of Winter should be used before every pull for the free runic power. It should also be used any time you have a spare global cooldown to generate some extra runic power and to make sure the buff does not fall off. This applies even if a shaman in the group is using Strength of Earth Totem, as the extra runic power is always useful.
 * If you are grouped with a shaman, you can ask the shaman to use Stoneskin Totem instead of Strength of Earth Totem. In addition to granting extra armor to the tank, it will also increase your attack power if you have the Bladed Armor talent. Note however that Stoneskin Totem does not stack with a paladins' Devotion Aura.