A player attacks with her Griffin Sentinel. This would normally cause Griffin Sentinel to be become tapped, but because it has vigilance, this means that it remains untapped and thus can block any thing that could attack her next turn.
- 702.20a. Vigilance is a static ability that modifies the rules for the declare attackers step.
- 702.20b. Attacking doesn't cause creatures with vigilance to tap.
- 702.20c. Multiple instances of vigilance on the same creature are redundant.