Hello!
I have made a system where I use body velocity to create a ground pound effect like in super mario brothers. The only problem is that when I do this the player gets flung. I have tried to anchor the player, stop the players velocity, get the players orientation and set their orientation to before the force was applied. All to no avail. Any and all help is appreciated 
You could replace the BodyVelocity with a VectorForce instead.
Use a prismatic constraint, and slide the player from the top of the constraint to the bottom!
This method seems weird if you want the Character to move while they stomp ( You can move while you stomp in super mario brothers if you fall for long enough ).
initially you’d connect the velocity to the constraint, so the direction being traveled is how the attachments translate, but then it could be a function that connects the UserInputService to further translating the attachments to get that midair control
But that seems like more Code for something you could just use VectorForce for ( not to mention that VectorForce takes an absoule amount of Force which allows you to fine tune fall speed ).
Somehow there has to be an incredible amount of force without a fling, what about welding/anchoring the torso on impact?
About the fling. OP might be using a BodyVelocity with Inf maxforce which would explain why the Character is getting flung.
Thank you! I’ve been tweaking around with vector force and it works perfectly. I never even knew vector force existed thanks!