en.yml

en:
  karma:
    admin: "admin title"
    level_-1: "title1"
    level_0: "title2"
    level_50: "title3"

some_view.html.erb

<%= t karma_title(@user) %>

user_helper.rb

module UserHelper

    def karma_title(user)
        return "karma.admin" if user.admin?
        "karma.level_#{user.karma}"
    end
    
end