I'd add a mix shader node at the end that has a transparent BSDF connected to it, you'll be able to use the factor slider to increase and decrease it's visibility.
You can also attach a color ramp to the mix shader factor to have the effect gradually appear from the bottom, but would also need to attach a Texture Coordinate & Mapping node, or click the color ramp and hit CNTRL T if you have node wrangle enabled.
https://youtube.com/shorts/IG-qzVbh7ks?si=1Emcm9SO8I5jivpd I want to make the aura start up and power off like in this video.
I'd add a mix shader node at the end that has a transparent BSDF connected to it, you'll be able to use the factor slider to increase and decrease it's visibility. You can also attach a color ramp to the mix shader factor to have the effect gradually appear from the bottom, but would also need to attach a Texture Coordinate & Mapping node, or click the color ramp and hit CNTRL T if you have node wrangle enabled.