Blackwhip ability from My Hero Academia.

Keep in mind that settings may vary slightly between different versions. See below for more details.

When I tested this with different checkpoints and LoRAs, it seemed to work quite well.

Illustrious:

A LoRA weight of 0.9 works great, though you can adjust the strength as you prefer.

Prompts I usually used:

blackwhip, black and green energy, coiled around bod, green glow,