Undercity Eliminator

• WWizards of the Coast2024-02-02
  Official Ruling
  You don't choose a target at the time Undercity Eliminator's ability triggers. Rather, a second "reflexive" ability triggers when you sacrifice an artifact or creature this way. You choose a target for that ability as it goes on the stack. Each player may respond to this triggered ability as normal.

Rulings via Scryfall