Tenth District Legionnaire

• WOTC Official Reminder Textofficial rules
  Scry — Look at the top N cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.

• WWizards of the Coast2019-05-03
  Official Ruling
  You scry 1 even if you can't put a +1/+1 counter on Tenth District Legionnaire, most likely because it has left the battlefield.
• WWizards of the Coast2019-05-03
  Official Ruling
  Tenth District Legionnaire's ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.

Rulings via Scryfall