Techno Blast inflicts damage and has no secondary effect. The type of Techno Blast depends on the type of Drive held by the user, being Normal-type if there is none held, and Electric, Fire, Ice or Water with the appropriate Drive.
Techno Blast is the only legendary signature move that the user does not get STAB on.
Ironically, Techno Blast is inferior to Genesect's other moves; as Flamethrower, Ice Beam, and Thunderbolt are superior in power, have more PP, and sport additional effects. The exception is when Genesect is holding the Douse Drive, as it does not have access to any Water-type moves other than Techno Blast and potentially Hidden Power which is limited to a power of 40-70.
This move is similar to Arceus' signature move, Judgement, in that the type of the move changes depending on the item that the Pokemon is holding: Arceus' Plates and Genesect's Drives.