Choose a card type. Target opponent reveals their hand. Blood Oath deals 3 damage to that player for each card of the chosen type revealed this way. (Artifact, battle, creature, enchantment, instant, kindred, land, planeswalker, and sorcery are card types.)
All permanents are artifacts in addition to their other types.
All cards that aren't on the battlefield, spells, and permanents are colorless.
Players may spend mana as though it were mana of any color.