I was thinking and I came up with this... You would find Santa (Jack frost dressed as Santa) in Varrock and you talk to him and he says "ho ho ho" and you realize it sounds different.. When you say "Your voice sounds different Santa" and Jack Frost teleports you to where the ice giants and ice warriors are. You then have to defeat a number of ice giants and ice warriors and collect "clue scroll" that gives you clues to where the real Santa is. He will be trapped in a cage and you will have to defeat Jack Frost and pick up a crystal key to free Santa from the cage. He will then ask "thank god, you saved me" and we say something like "oh it was nothing" and Santa offers us a reward. The reward could rather be a mystery box that contains rares... or double xp for 2 hours or something you want to be as the rewards.
Thanks for reading my idea
~Jah
Thanks for reading my idea
~Jah