Kels, Fight Fixer

• WOTC Official Reminder Textofficial rules
  Menace — This creature can't be blocked except by two or more creatures.

• WWizards of the Coast2020-06-23
  Official Ruling
  A legendary permanent that is put into a graveyard because of the "legend rule" isn't sacrificed.
• WWizards of the Coast2020-06-23
  Official Ruling
  You can activate Kels's last ability even if nothing's about to destroy it and even if it already has indestructible.
• WWizards of the Coast2020-06-23
  Official Ruling
  If you sacrifice Kels, its middle ability triggers. It also triggers for any other creatures you sacrifice at the same time. You can sacrifice Kels to pay the cost of its own ability.
• WWizards of the Coast2020-06-23
  Official Ruling
  Kels's middle 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, such as Kels's last ability.
• WWizards of the Coast2020-06-23
  Official Ruling
  While resolving Kels's middle ability, you can't pay more than once to draw more than one card.
• WWizards of the Coast2020-06-23
  Official Ruling
  If you sacrifice a permanent as part of a spell or activated ability's cost, Kels's middle ability will resolve before that spell or ability.

Rulings via Scryfall