There are 4 different Seasonal Events in Portal Knights, where you can complete special quests and get unique rewards during certain seasons. These are all tied in with real life seasons, and the days where the event runs are on:
20 February when the Spring Event is live.
27 March when the Egg-Hunt Event is live.
31 October when the Halloween Event is live.
24 December when the Christmas Event is live.
You can only complete these events during these single days, unless you know a workaround (which you will learn in a minute).
So, how do we get access to the Seasonal Events in Portal Knights without waiting for the right season? The answer is actually very simple; just change the date on your system!
By changing the date to any of the four above dates, the event will spawn in your worlds. You don't even need to play in offline mode or anything like that, since event spawns are handled by the game client, and not a server.
This smart trick works on both PC and all consoles, so just go ahead and change the date to get the Seasonal Events going!