Soul Swift (ソウル神速, Sōru shinsoku) is an ability introduced in SD31. It is an evolved form of High Speed and Violent Swift. So far, only two green spirits have this ability, The WhirlwindNinja Kirikage and The StarKnight HerculesΩ (revived version).
The effect reads:
- (Flash Timing) Soul Swift (Every Attack Step) This spirit card may be summoned from your hand during the Flash Step by using (Soul Core) from your reserve to pay the entire summon cost. In that case, the cores to be put on this spirit must be moved from your reserve.