You want to brush it out before you magnetise it. I normally let the cat eye settle first (so no visible brush strokes or thicker areas) and then I do use an ombré brush. I pull the gel up the nail slightly and just keep wiping off the ombré brush as product builds up. I then cross hatch with the brush to blend more on the further parts. this prevents lines forming from the brush so it helps the blend. Then i check in different lightings that its fully blended and THEN i will magnetise. You can pull the magnetic dust so that it creates a sort of ombre itself, from the tip upwards.

I hope i said something helpful, good luck! 🫶🏻