Start with the counter (press
as the enemy attacks), since that's a movement that you need your enemy to perform and can't wait.
Quickly press
to use a sign. Quen is my favorite since it feels the fastest to cast. Axii is also nice cuz it can stun the enemy keeping them still.
Then hit the enemy once with a sword (
)...
... and finally throw (without aiming) a bomb of your choice by quickly pressing the
button.
Achievement unlocked. In fact I had to try a couple of times and a few variations until I was fast enough.
If this solution helps you in any way, please leave it a thumbs up to let me know. Thanks!