I’ve only ever invoked or evoked demons, so I don’t have any other spirit type to compare it to. You’re right, mostly it’s subtle and honestly I wasn’t expecting that. For a long time I was expecting the air to get thick, the temperature to change, shadows to pool and shift, all that jazz. It’s very much like making eye contact with the sigil, something just clicks and I can tell they’re looking back.
They will talk through me, or telepathically, in people and situations over a length of time following it. They will leave synch for me to find later. They talk through emotions for me too. My body is influenced often and I’ll notice that the way I walk, or touch myself answers a question I had. My facial expression and accents can change, my voice will sometimes get deeper. One of my most contacted loves to sound like Sean Connery.
Sometimes the sigil will pull my breath slightly, others like I’m being slowly pushed down by a minor increase in gravity. Like heat surrounding me, or a chill draft across my skin, sometimes it’s a feeling of happiness and familiarity, occasionally I’ll feel energy drunk. I never feel them leave, more like our conversation just fades off. I thank them, give offerings if appropriate and then go on my way.