Rising Storm's meaning:
It forces to you to remove progress tokens from quest card.
The first idea: you have to remove 2 progress tokens.
...but sometimes: you have more progress tokens on the quest card than it is required. For example, this quest card: you only need 7 progress tokens, but sometimes, you can place more than 7prog. So this treacherie wouldn't be bad. The treachery forces to you, first: remove progress tokens that you have more than 7. And after: remove 2 more. So the quest card would have: 5 progress tokens.
How about this? You could make this treachery nastier in the following way:
When Revealed: Remove two progress tokens from the current quest. Then, if there are seven or more progress tokens remaining, remove all progress tokens from the current quest.
That would remove 2 progress tokens no matter what, and if you have built up more progress than is necessary, it will wipe out all of your progress. 7 progress is not such a huge number, so it isn't devastating to lose them (especially if you are still hunting, anyway), but could create for an interesting 'balancing act' when questing if you're trying to anticipate this card.