A Guardian of Icecrown is a crypt lord summoned during Phase 3 of the Kel'Thuzad encounter in Naxxramas. On normal (10-man) difficulty, when Kel'Thuzad shouts "Master! I require aid!", two Guardians come through the portals within Kel'Thuzad's Chamber. On heroic (25-man), there are four Guardians. The Guardians have a self-buff known as Blood Tap, which increases their damage by 15% and their size by 10% and can stack up to 99 times. When Kel'Thuzad is defeated, the Guardians will flee.
The Guardians are immune to all CC (including Shackles) in both normal and heroic Naxxramas. The tactics for dealing with the Guardians on normal difficulty are:
- Second tank with dedicated healer tanks the Guardians away from the raid while the main tank and all DPS focus on Kel'Thuzad. The Guardians have too much HP to attempt to kill at the same time, so in order to prevent a wipe, all DPS remains on Kel'Thuzad until he is killed (and it's recommended you do it quickly, as the stacking self-buff can become problematic over time).
- Main tank holds both Kel'Thuzad and the Guardians, with all DPS remaining on Kel'Thuzad until he is killed.
The 25-man tactic appears to favor the off-tank approach (with one tank focused on Kel'Thuzad, the off-tanks on the Guardians). Two to three off-tanks are recommended for the Guardians, with dedicated healers. Two Guardians appear at first, and then two more after 10 seconds; by this time, the designated off-tank(s) for the first two will have gained their aggro, allowing the other off-tank(s) to get aggro on the next two.