Atzocan Archer

• WOTC Official Reminder Textofficial rules
  Fight — Each of those creatures deals damage equal to its power to the other.

• WWizards of the Coast2017-09-29
  Official Ruling
  If Atzocan Archer isn’t on the battlefield as its triggered ability resolves, or if the target of that ability is illegal, no creature will deal or be dealt damage.
• WWizards of the Coast2017-09-29
  Official Ruling
  You must choose another target creature (if able) as Atzocan Archer’s triggered ability is put on the stack. You choose as that ability resolves whether those creatures fight.
• WWizards of the Coast2017-09-29
  Official Ruling
  Atzocan Archer’s ability can target another creature you control (such as a Dinosaur with an enrage ability).

Rulings via Scryfall