I'm not sure what you mean by soft magic exactly.

I mean, suppose you have a game like dungeon world, where all moves have mechanical impact, and so do the DM's responses. It may not specify the radius of a fireball. Is that soft magic?

One way you could make the Fae really alien to your game is to use a different core game mechanic within the Fae.

Imagine converting player actions into PBTA rough equivalents, and imposing results based on those rolls. There would be a rigid system, it just wouldn't be the base D&D mechanics. When you go to attack them, you'd be doing a Hack and Slash. But without cold iron or the Fey's true name, maybe that move just wouldn't work.

Fae intrusion into the middle kingdom would make a pocket of Fae here. Outside of it, it is just a creature. Inside of it, Dungeon World mechanics apply. Or something similar.

---

Have you read about the ant-cthulu?

https://tyrantisterror.tumblr.com/po...hachan-weasowl

probablybadrpgideas

If Cthulhu can be summoned by humans who are so far beneath it, why cant humans be summoned by ants? The answer is they should be.

20thcenturyvole

Well if a bunch of ants formed a circle in my house Id certainly notice, try to figure out where theyd all come from, and possibly wreak destruction there.
(and it goes on)

Under this model, the Fae's interest in humans is akin to a humans interest in ants. Or maybe a human's interest in bears, if you want to make humans more threatening.

The bears mostly live in places where humans aren't. The humans go visit these places for amusement (camping, etc). They aren't interested in the bear's resources. They are sometimes annoyed by the bears intruding on human areas, or harming humans, but really, some dumbass goes off and taunts a bear and gets mauled, that is on that human. We might euthanize that specific bear if we find them.

Bears who enter human areas, well, we put them to sleep and relocate them. Or, in the case of Churchill manitoba, there is a bear jail, and a bear bypass to get the bears to not walk through the city.

The Faewilde would be where the Fae live. Humans who wander in there are like bears. Dangerous curiosities. Usually the humans stay at the edge of the Faewilde, so are tolerated.

Fae wander into human lands (the middle kingdom) not out of need for human resources, but for Fae reasons that don't align with human ones. Maybe they are setting up the equivalent of an observatory on a mountain top. To a bear, this makes no sense; are they claiming territory to mate? Do they want the tasty berries? No, they are apparently building a ridiculous contraption that does nothing of any use to look at the stars in the night sky. Why are they doing that? Basically amusement and social status and a cult they call "science".

These humans can't even smell who lives in an area, and are physically ridiculously weak. They have next to nothing a bear values. Except sometimes they have tasty food, some of which makes you sick.

Making the Fae be in a different ecological niche than mortals, alien in their needs and wants, and apply different mechanics to how things are resolved in the Fae, would make them really alien. Their magic might be as hard or moreso than base D&D magic, just alien.