Unlike many Blackwing Synchro monsters, Raikiri does not require Blackwings in order to be played. However, if you happen to use a Blackwing monster as Synchro Material for Raikiri, he becomes a Tuner monster himself. While this makes him able to help players summon higher level Synchro monsters, this is hardly the best thing about Raikiri.
Once per turn, Raikiri has an effect that allows you to target a number of cards your opponent controls up to the number of other "Blackwing" monsters you control. You then can destroy those cards. With a field full of Blackwings, this means you can destroy up to 4 cards per turn. If that seems incredibly unfair, well, it is. Essentially, your opponent needs either an immediate answer to Raikiri's summoning or some way to negate the activation of his effect.
Raikiri the Rain Shower is probably the most powerful Blackwing monster ever printed. Will Raikiri propel Blackwings back into the Yu-Gi-Oh competitive spotlight?