Slime is exclusive. Instead of doing damage you create a puddle of Slime. This does no immediate damage and has none of the normal effect of the blast. Instead, you set up a nauseating slime patch with a diameter equal to your Magic in meters, that will nauseate anyone inside it. The slick is clearly noticeable, but transparent, and lasts until the end of the Sequence. The puddle has no game effect after the end of the sequence, but is still there and still foul until cleared away. If you spend a Magic point it lasts until dispersed (at least a few minutes).
Anyone in the slime patch must must make a Constitution roll against your Magic as he tries to take an action. If he fails, he gags and simply loses the shots he intended to use for the action, no movement or action is successful. This does not apply to activedefenses.
Damage Immunity to Water or Life rather than Blast protects against this.
An exclusive metablast has none of the normal effects of that blast, including any other metablasts that would ordinarily apply. In effect, an exclusive metablast is a separate effect that replaces what the blast normally does. Still, it takes it's appearance from the blast it is used with, if it does any damage it is of the same type, and a Damage Imunity that would protect against the blast also protects against the exclusive metablast.
If you can only use the blast to create slime, and cannot use it for plain damage, this metablast schtick is free.