Dwarven Warriors

Oracle Text

T: Target creature with power 2 or less can't be blocked this turn.

Card Rulings

10/4/2004 The ability can be activated after a creature is blocked, but it has no effect. Once a creature is blocked, it can’t be unblocked.
10/4/2004 If you increase the power of the targeted creature after the ability resolves, it still can’t be blocked that turn.