Good deception is not a faster wrist. It is an identical preparation for three completely different shots.
Opponents read the net from your racket face, not your eyes. If the tumble and the lift look different at preparation, no amount of wrist speed saves you.
Start by grooving one preparation position for the net kill, the tumble and the cross lift. Film it and check that the first sixty percent of the movement is identical.
Only then add the late change. The deception lives in the final ten centimetres of racket travel, not in a big swing.
Practise against a partner who calls the shot as they see it. When they start calling wrong more than half the time, the disguise is working.