Scoped Activerecord query

I have a User model with a scope :superhero and I want to do an AR
query along the lines of:

@avengers_powers = Power.where(etc.).includes(User.where( #{this is
where I want to limit by superhero scope} ))

My users schema is:

create_table "users", :force => true do |t|
    t.string "uid"
    t.string "name"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string "token"
    t.text "ability"
    t.string "location"
end

My user model has:

scope :superhero, where("ability like '%laser vision%' OR ability like
'%invisibility%'")
scope :hobo, where("location like '%cardboard box%'")

Seeing as :superhero and :hobo aren't attributes on the user model,
how would I query it?

@avenger_powers = Power.where(whatever).includes(User.all.superhero)