Aegean Miles+Bonus releases every few months Happy Miles up to 30% off awards on selected routes.
The latest patch is valid for travel between December 1 – February 29, 2016 (blackout period December 18 – January 11.
You can access Aegean’s web page for this offer here.
Here are the discounted routes.
You should check the prices for paid tickets as well, as they are sometimes low on Aegean and redeeming then makes no sense at all.