I don't want this to be in response to Zeiler's Gencon-winning deck. It's not. I knew about Robert-Maesters before Gencon. It can be done with Renly (influence-standing), Satcliffe (Ironborn) and a few other standing charatcer cards (Marya + Inn of the Standing Man), etc. But....once all six chapter packs are released and all of the chains are available, there are a few abusive combos and some broken, infinite combos out there. What errata would I recommend? Make the Maesters that target of the chains. Errata the Maester's Agenda to "attach to a character with the PRINTED Maester trait.
How about Prince's Plans? This card is awesome! (Awesomely broken!) Imagine a deck with Westeros Bleeds x3, Red Vengence x3, Burning in the Sand x3, Orphan of the Greenblood x3, Prince's Plans x3 add in a few Plots (Loyalty, Valar, Muster, Lineage and Legacy, etc.). Finally, throw in The Viper x3 and a character-lite deck is pretty nasty! I think Prince's Plans should be restricted, but just remove Burning from the list above and I can still make a very nasty deck. If CP #4 was available for Gencon, you would've seen Martell Knights of the Hollow Hill as the predominant deck. Should the card be banned? I'm not sure. Definitely restricted!
What do you guys think? Any other cards?