Fireblade Artist

• WWizards of the Coast2019-01-25
  Official Ruling
  Fireblade Artist's triggered ability goes on the stack without a target. While that ability is resolving, you may sacrifice a creature. When you do, the reflexive triggered ability triggers and you pick a target opponent or planeswalker to be dealt damage. This is different from effects that say "If you do . . ." in that players may take actions after you've sacrificed the creature but before damage is dealt.

Rulings via Scryfall