Endbringer {C}

Text:

Untap Endbringer during each other player's untap step.
: Endbringer deals 1 damage to any target.
{C}, : Target creature can't attack or block this turn.
{C}{C}, : Draw a card.

Rulings:

• 1/22/2016 Endbringer untaps at the same time as the active player’s permanents. You can’t choose to not untap it at that time.
• 1/22/2016 If an effect states that Endbringer doesn’t untap during your untap step, that effect won’t apply during another player’s untap step.
• 1/22/2016 Activating the second activated ability after a creature has legally been declared as an attacker or blocker won’t change or undo that attack or block.