He could do many things to prepare, like practising a particular branch of magic that he knew of but avoided using because of its high risk. A lot of rituals could be powered by the life and soul of an enemy. And those could equally well be harnessed in his smithing experiments, provided he could find a forge nearby. Magic that dealt with ritual sacrifice was powerful and had equally powerful consequences that he generally did not want to deal with. But now, all bets were off, and there were ways to deal with most negative consequences. There were plenty of Bolton men patrolling in the Wolfswood, still searching for deserters and stragglers from Stannis" army. They would make very good material for his foray into ritual magic.