GMG has renewed their 20% off discount on the newly released Mass Effect 3. The N7 Digital Deluxe edition is also discounted. No voucher code necessary.
The deal is limited to North America and anyone that uses the greenmangaming.co.uk domain.
Keep in mind this game requires Origin. It has a 92/100 metascore but the user score is only 3.5/10 :P.