Cast Eightfold Maze only during the declare attackers step and only if you've been attacked this step.
Destroy target attacking creature.
10/1/2009 If all the attacking creatures attack your planeswalkers, you can’t cast Eightfold Maze. To cast it, a creature needs to have attacked _you_.
10/1/2009 If you’re able to cast Eightfold Maze, it can target any attacking creature (including one attacking a planeswalker).