The effect has two aspects: the portal appearing, and then the looping effect that persists.
Black soot pixels appear first with the ground decal
The portal's core appears, with more pixels & flame
Before creating prefabs, I like to take notes on the aspects of each phase of the effect and the elements I see present. This makes things a lot clearer when actually starting in Unity.
Distinct elements present in the effect are recorded, so I can plan the different prefabs I want to make for the combined effect.
I used a decent screenshot of the floor decal shape to recreate my own HD alpha maps. This required stretching the reference OUT of perspective to an orthographic grid view that fit in a square. Once that was done, I could redraw both the dark shadow and the neon lines.
I ended up using 3 images: the black shadow, the neon line core, and the neon line glow.
I also created my own alphas for the ripple and the blue flame base.
Ripple & Flame Alphas
Below, you can see my unity prefabs that make up the final effect, as I've isolated each in view.
Attempts & Iteration
An example of an early version of the effect, and notes I would take down when compared to the reference. The accuracy of the study comes from not only making the prefab pieces, but timing them to each other. Refinement in this study included extra work on the neon line effect in game to understand how to make the neon core, neon glow, and shadow decal "pulse" on the ground, both with opacity and emission. Once achieved, this gave the sense of glowing power moving through the neon lines.
Day 1 - Decals placed + pixel transition
Day 2 - Fade animations & emission noise
Day 3 - Opacity noise
With each of the prefabs fine-tuned based on notes and comparison, I arrived on a visual that more closely resembles the reference footage, with better understanding of the contributing elements.
final reproduced effect in Unity
Reference for Comparison
I hope to have more studies to include in this series soon!