User blog comment:Blake Xi/Why types don't matter/@comment-26335574-20150921131849

IMO, Oracle has always been a great type to have on healers, as the healing they do scales with their REC; more REC means more heals

that being said, Guardian is also a good type on healers; it offers some survivability thanks to extra armor, cause the penalty of slightly less att is completely invisible on units from who you don't expect damage in the first place