Spaak is an enemy in the Subspace Army that resembles a white, mechanical cloud that tries to ram into you. When attacked, it turns black and becomes even more aggressive.
In its base white form, it fires slow electric balls while staying stationary as it attacks. In its damaged black form, it fires fast lightning beams with high knockback, while at the same time moving more evasively. These attacks can be reflected, countered and absorbed. It will take double damage when the battery on its back is attacked.
A Subspace Army member who is mostly cloud but also reveals mechanical parts, like electrodes and batteries. In most cases, a Spaak is white and fires lightning, but it turns into a dark cloud after taking damage and chases you with fast lightning strikes. Its weak point is the battery on its back--attacking that should make it pretty easy to take down.