[CONT]: Sentinel (You may have up to four cards in total with Sentinel in a deck) [AUTO]: [Choose a card from your hand, and discard it] When this unit is placed on (GC) from hand, you may pay the cost. If you do, choose one of your vanguards that is being attacked, and that unit cannot be hit until end of that battle. Then, if there is a card named "Flowers in Vacuum, Cosmo Wreath" in your drop zone, choose a card from your damage zone, and turn it face up.