The MonaDACUS (Monado Deactivated Art Canceled Up Smash), previously referred to as the SABDJCUS (Speed Art Buffered Deactivation Jump Cancelled Up Smash) is a Smash 4 technique that acts similarly to the DACUS technique in Brawl (as referenced by the name), using the MABD technique. However, it is extremely situational and hence almost useless in actual play.
In Ultimate, this technique was removed, since it relied on MABD to be performed (which has been patched out indirectly).
By canceling out of the Speed Art during an animation where Shulk can buffer an Art deactivation, Shulk will keep his increased ground speed for a few frames while losing Speed's increased ground friction, allowing him to slide even further and punish opponents with a jump-canceled up smash. This helps Shulk hit opponents that he usually wouldn't be able to reach. As the technique also involves canceling the Speed Art, it also deals more damage compared to staying in Speed Art and up smashing, as Speed reduces damage output. It should be noted that this technique gains almost no distance without a jump-canceled up smash.