for example this user https://softwareengineering.stackexchange.com/badges/44/necromancer?userid=16337 had got the necromancer badge today as a question was merged with the one which was older than 60 days. i.e How do people read big technical books? Does this mean every one who gets up voted above 5 votes automatically earns this badge? . IMHO the actual badge description makes this a rare and a relatively hard badge to earn.
Answered a question more than 60 days later with score of 5 or more
And it is to be earned by the user when he resurrects an old question by answering it or by editing an existing old answer.
Merged Questions Do not consider the Effort Portion of the user in answering a 60 days old question as this is already done implicitly by merging.