The effects in that video are just stand ins; I haven't even had a chance to get started on the actual effects yet, which are actually intended to be some kind of dimensional tear as the p-space bubble/mass returns home.
This is a pretty early go over of the idea, with complementary Shantae. It's changed somewhat since I drew this up (decided to ditch the shimmering effect, for one); I have a pretty good idea of how to handle the "explosion" effect but the pulsing/shrinking bullet thing is very likely going to need to be hand animated, which is gonna be a pain.
Also it'll need sound effects that kinda give that feeling; you know that feeling, when the terrifyingly thin walls of our reality are shattered, even if only for an instant, and the maddening vistas of what lays beyond are revealed. And for just a moment, the Monsters from
the IdP-Space can come through.
Wait, where was I going with this?
Anyway, should be pretty badass if I can get it all put together right.