Do creature effects trigger every time they move base?
No, Invader grants a victory point when it's played, not when it's moved.


  Play: You play a card
  when it’s one of the
  free cards you get in
  step 2, or any time an
  ability specifically says
  that you’re playing it. A
  card’s ability happens
  when you play it. When
  cards are moved, placed,
  or returned, they’re not
  being played, and their
  abilities don’t happen.
  
  Move: This lets you
  move a card from one
  location to another.
  Moving a card does
  not count as playing it.
  Minion abilities do not
  happen when you
  move a card.