Plague Wight

• WWizards of the Coast2019-01-25
  Official Ruling
  If all creatures blocking Plague Wight die, Plague Wight remains blocked. It won’t assign any combat damage.
• WWizards of the Coast2019-01-25
  Official Ruling
  An ability that triggers when a creature becomes blocked triggers only once if two or more creatures block it.
• WWizards of the Coast2019-01-25
  Official Ruling
  If Plague Wight leaves the battlefield while its triggered ability is on the stack, the creatures that were blocking it before it left the battlefield get -1/-1.

Rulings via Scryfall