The swirling portal was a piece of scenery that blocked the access to The Heart dungeon. It was the last obstacle in place between the players and the dungeon, and would reward Divination experience as players break it down after the event.
Breaking down the portal at level 99 Divination gives 76.4 experience every 3.6 seconds (76,400 experience per hour), making it a viable training method. Every ten actions (36 seconds) it is required to click on the portal again as it overwhelms the player, interrupting the training.
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