-1/-1 counter question

[Prplprince]

Example: I have  {Nantuko Shade} on the battlefield and it is a 5/4 after pumps. My opponent  {Black Sun's Zenith}  for one and end his turn. Can I pump Nantuko Shade at the beginning of my upkeep or can I not respond to the zero toughness?

[Remillo]

Example: I have  {Nantuko Shade} on the battlefield and it is a 5/4 after pumps. My opponent  {Black Sun's Zenith}  for one and end his turn. Can I pump Nantuko Shade at the beginning of my upkeep or can I not respond to the zero toughness?

What happens is that at the Clean-up step, the "+1/+1 until end of turn" effects wear off.  The game then checks the game state and sees that your Shade has 0 or less Toughness, and then puts it in to the graveyard before either player has a chance to do anything, and before it actually becomes your turn.

[Prplprince]

Oh ok thanks