[HELP] Knockback fluid into the server with another player (not is NPC)

Hi guys, how can I do this 3th movement (the hit from above into the air to floor) fluid into server script, I tried with bodyvelocity, and linear, but the second have bug, and the first doesnot start fast when I´m playing with another real player (not is NPC), some ideas? See this video please:
https://gyazo.com/7b5a8f3c78c576fefd9823fb114e2e43