Star-vader, Strange Dragon

:When this unit is placed on , if you have a vanguard with "Chaos" in its card name, until end of turn, this unit gets ":When this unit attacks or boosts ([Boost]), if that attack is attacking a vanguard, your opponent chooses one of his or her rear-guards, and locks it. If your opponent could not lock, this unit gets +5000 until end of that battle.". :If your opponent has a locked card, this unit gets "Boost ([Boost])".