Movement breaks Intense Cold, so just keep strafing/jumping/moving, and avoid spells with long cast times. If you get rooted by Crystal Chains, use or PvP trinket or whichever class/racial abilities you have to get out of movement-impairing effects. If you have a priest in the group, have all group members stand close to each other and use .
Higher leveling characters attempting to solo this achievement should ensure that Intense Cold is cast before killing Keristrasza, since killing her before she can cast Intense Cold will not give you the achievement.
- Patch 3.0.2 (2008-10-14): Added.