Mazirek, Kraul Death Priest

• WWizards of the Coast2020-08-07
  Official Ruling
  If you sacrifice a permanent as part of casting a spell or activating an ability, Mazirek's last ability will resolve before that spell or ability.
• WWizards of the Coast2020-08-07
  Official Ruling
  Mazirek's last ability is a triggered ability, not an activated ability. It doesn't allow you to sacrifice a permanent whenever you want; rather, you need some other way of sacrificing permanents.
• WWizards of the Coast2020-08-07
  Official Ruling
  If you sacrifice Mazirek and other permanents at the same time, Mazirek's last ability triggers for the other permanents.
• WWizards of the Coast2020-08-07
  Official Ruling
  A legendary permanent that is put into a graveyard because of the "legend rule" isn't sacrificed.

Rulings via Scryfall