Menma creates a dark purple Rasengan-like orb of chakra surrounded by a series of white rings of chakra that orbit the main sphere. These rings then align into one disc-like shape around the orb, causing the rings to resemble planetary rings. It matches Naruto's Sage Mode Wind Release: Rasenshuriken in power.
The technique's name is a pun, similar to certain techniques of Kumogakure ninja, in which it has an English name with a given kanji that somewhat match the pronunciation. In this case, "輪虞" is pronounced as the English word "ring", but literally means "fear wheel".
The proper spelling of the technique's name was first revealed in Naruto: Shinobi Masters, a Japanese social game available for iOS and Android phones on the GREE mobile social gaming platform.