Light turn on - effect selection with drop-down

Hi everybody,
I have a Nanoleaf Shapes light set connected to HA and want to control the effects with a drop-down menu.
I am using a Mushroom: Select frontend card tied to a Dropdown Helper object that has all the 16 different effect names in the list.
My question is: when calling the Light.turn.on service how do I pass the effect names to the “effect” section at the bottom of the service?

I think I’ve answered my own question…

{{ states(‘xxxxxx’) }} in the effect name field.

Unfortunately the HA documentation is somewhat confusing for newbies. Some more examples regarding states would be great.