Pardon me, but it's a whole new set of rules from here on.
[CONT]: Sentinel (You may only have up to four cards with "[CONT]: Sentinel" in a deck)
[AUTO]:[Choose a «Link Joker» from your hand, and discard it] When this unit is placed on (GC), you may pay the cost. If you do, choose one of your «Link Joker» that is being attacked, and that unit cannot be hit until end of that battle.