Ah, Springtime. I think we all know that moment – after a long, cold winter, that first brush of warm, spring air grazes our cheeks, bringing with it the hope and promise of new life, better weather, and longer days.

Now imagine that fresh spring breeze tried to strangle you and tear you to shreds. You have an Invisible Stalker!

One of the most important things to remember about the Invisible Stalker is that it’s not just some random thing that comes hunting your Players. It is an assassin, but not like those common cutthroats and poisoners. It has been summoned from the Elemental Plane of Air through arcane means, and sent specifically after someone. It’s at least as intelligent as a Commoner, and has substantially better Wisdom, which makes it more dangerous than you might expect.

This implies a lot about this creature. For example, it’s very likely that the Stalker spends a lot of time watching your Party. It’s already invisible, can squeeze through tiny spaces, and would have no problem waiting until its target is alone. Its intelligence allows for harassment and psychological warfare, chipping away at its prey’s sense of safety and well-being.

For you, this means building suspense. Candles that flicker when there’s no breeze in the room. A chill in the air. A bird falls from the sky, its neck snapped, and when your Players dream, they dream of being watched. If you do it right – blowing pages out of their hands, parting the mists before them with nothing there. Maybe a cloak falls from a hook. A mirror seems to reflect a pale form that isn’t there when you turn around – your players should be good and paranoid, and ready for when your Invisible Stalker finally makes its move, taking on its target when they’re alone and vulnerable.

Of course, the next question you need to think of is: Who summoned it? There are so many options available to you that almost anything can fit your campaign. Perhaps it’s an actual enemy, someone your Party is making their way towards and they’ve gotten a little closer than they’re comfortable with. It doesn’t have to be a magic-user, either. That mining magnate who’s got Dwarven slaves digging mithril might not be able to summon an Invisible Stalker themselves, but they’ve got the money to hire someone who can. Will that summoner give up their employer when your Party gets to them? What else do they have up their sleeves?

It doesn’t even have to be a formal summoning. Maybe your Party tripped an ancient ward or a latent enchantment in their sloppy exploration of a temple or a dungeon. This Stalker was never meant to be pulled in from the Plane of Air, but now it has – and it wants your Bard’s head in a bag. Whatever brought it here, it’s furious. And will not be stopped.

Once the Stalker enters combat, you should lean on the challenge of fighting an invisible enemy. You can make the fight more emotional than mechanical, by having wounds that seem to appear from nowhere, Party members suffocating in an otherwise empty room, and a target that no one can really get a bead on. Disadvantaged swings hit nothing, and even the ones that do hit are less effective – the Stalker is resistant to Bludgeoning, Piercing, Slashing damage, magical or otherwise, and is immune to a lot of the conditions that would otherwise give your players a fighting chance.

Savvy players can, of course, get around this. Faerie Fire is a great early spell that could highlight your Stalker easily. If it’s in the same space where they cast the spell, of course. Other spells, such as See Invisibility or True Seeing would do a lot to help your Party triumph, but those won’t be available until higher tiers.

And, of course, gods forbid your players happen to be carrying around a bag of flour. Not saying that’s happened in my game, but I’d be entertained beyond measure if it did.

Of course, if you’ve done your job really well, they should be planning for some kind of attack from the shadows. They’ll be bracing for a dagger in the dark, not for the air itself to turn against them.

However you do it, think like a horror movie: narrow corridors, flickering torches, a Party that splits up for just a moment too long.

The end of this saga should be the price of summoning one of these things. What would a being like this want? It’s living wind, so it doesn’t want gold or gems like some mortal killer. Maybe it requires the breath of the caster, leaving them wheezing and weak for a time – something your Party might be able to take advantage of, if they move fast enough. Or the breath of a loved one. Is the death of your Party member worth a caster watching their own child gasp for air? How angry and vengeful is your villain?

The Invisible Stalker’s dying breath, should it be killed, could reveal something of its summoner. It may cry out in the voice of the one who summoned it.

Or a thin, childlike voice wafts away: “Mummy? I can’t breathe too good….”

If your villain is summoning a hateful, unstoppable, murderous wind, they’re someone with a story. Make sure your Players appreciate it.