Vandalblast

• WWizards of the Coast2024-01-12
  Official Ruling
  To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as an overload cost), add any cost increases, then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.
• WWizards of the Coast2024-01-12
  Official Ruling
  Because a spell with overload doesn't target when its overload cost is paid, it may affect permanents with hexproof or with protection from the appropriate color.
• WWizards of the Coast2024-01-12
  Official Ruling
  If you are instructed to cast a spell with overload "without paying its mana cost," you can't choose to pay its overload cost instead.
• WWizards of the Coast2024-01-12
  Official Ruling
  If you don't pay the overload cost of a spell with overload, that spell will have a single target. If you pay the overload cost, the spell won't have any targets.

Rulings via Scryfall