Pokkén Tournament‘s Burst Mode is designed primarily for momentum stealing; entering Burst, or “Burst Declaring,” is a safe panic button on wake-up, has an invincible 0 damage hitbox that pushes the opponent away on hit, and you get temporary access to the (mostly) safe Burst Attack each character has. Because of all the stuff it does, Nintendo went really out of their way to make sure you couldn’t just immediately combo into a Burst from an non-Burst Mode state.
But they didn’t go far enough.
As Mitchel explains, Phase shift points being reset after Burst Declare, combined with lingering hitboxes and assists means you can declare Burst, then immediately combo into Burst while the opponent is hit by some disjointed attack. How useful this will be in the long run will yet to be seen, but it seems like characters with fast Burst building should be able to make use of this well, such as Shadow Mewtwo.
Source: Mitchel