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** More Info here **
On 17 October 2011 the mechanics of Frost Dragons received an update. They were given a ranged attack, similar to Mithril Dragons, as well as a new rebounding effect. Each Frost dragon will attack with EITHER their ranged or magic attack for the entire fight; which style it will use depends on whichever attack is randomly used FIRST - so keep an eye on the first attack, and pray accordingly for that kill. When fighting Frost Dragons, a small blue orb will appear and start circling the dragon. It is important that you do NOT attack while the orb is out, as it will rebound any damage you would've dealt 100%. Therefore, it is important that you have your auto-retaliate switched OFF when fighting these dragons; when the orb appears, click away from the dragon to stop attacking and wait. The orb will circle 3 times before it disappears, after which you can resume killing your dragon.
This is the up to date Frost Dragon Guide.