It is an intresting way (You can also simply run into the castle; after the guards stop you, pause the game immediately after the conversation ends, and then click inside the castle again. They will not be fast enough to stop you a second time.)
to go back in Stormfist Castle AFTER my invitation in Stormfist Castle!
On that moment I haven't my Teleporter Stones anymore ... so after Iona's dungeon I can go in Stormfist Castle and take all the loot I couldn't carry with me the first time
Never discovered I can go in again without the use of my Teleporter stones