Beacon Bolt

• WWizards of the Coast2018-10-05
  Official Ruling
  If any exiled cards you own are face down, they have no characteristics. If they're normally instants or sorceries, they won't be counted.
• WWizards of the Coast2018-10-05
  Official Ruling
  If a card with jump-start is put into your graveyard during your turn, you'll be able to cast it right away if it's legal to do so, before an opponent can take any actions.
• WWizards of the Coast2018-10-05
  Official Ruling
  A spell cast using jump-start will always be exiled afterward, whether it resolves, it's countered, or it leaves the stack in some other way.
• WWizards of the Coast2018-10-05
  Official Ruling
  Beacon Bolt is still on the stack while you count your instant and sorcery cards in your graveyard and in exile. It doesn't count itself.
• WWizards of the Coast2018-10-05
  Official Ruling
  If an effect allows you to pay an alternative cost rather than a spell's mana cost, you may pay that alternative cost when you jump-start a spell. You'll still discard a card as an additional cost to cast it.
• WWizards of the Coast2018-10-05
  Official Ruling
  You must still follow any timing restrictions and permissions when casting a spell with jump-start, including those based on the card's type. For instance, you can cast a sorcery using jump-start only when you could normally cast a sorcery.

Rulings via Scryfall