Cost: 2. XP: 3.
Test Icons:

During your turn, exhaust Stealth: Evade. The chosen enemy gets -2 evade for this evasion attempt. If you successfully evade the enemy, disengage with it but do not exhaust it. Until the end of your turn, that enemy cannot engage you.

Ignacio Bazán Lazcano
Return to the Path to Carcosa #5.

Almost identical to the level 0 version of Stealth, for 3 XP you get an additional Agility icon, and Finn Edward's ability to Evade as a free action once per turn. This is further bolstered by the - 2 evade, making this a solid pickup. 3 XP might seem like a lot, but any enemy with an Agility of 2 or less is automatically evaded, unless you draw the auto-fail. Yet another benefit is that seemingly ever present inclusion of "a non elite enemy.", is missing from the card. This means you potentially can evade some big elites, turn after turn. It can also be used aggressively with Waylay, if the investigator can take it, potentially turning Waylay into a 1 action kill, or with Sneak Attack, for a cool 2 test-free damage. Might be overkill in a Finn deck, but also turns him into a pretty great dodge tank with just a bit of support. I personally think it's a great card, with a lot of potential.

oCCult · 7
It doesn't work with Waylay, though. Waylay requires the enemy to be exhausted and this specifically doesn't exhaust the enemy - it just disengages it from you. It also can't trigger lvl 0 sneak attack. So it's a bit more limited than a free evade action, and I think it's only really great in solo. At higher players counts, you're not so much evading the enemy as you are pushing it off on whatever other investigators happen to be at the location and I think that's a bit less valuable. — bee123 · 24
In Multi it can be helpful for the cluer to move on their own or push enemies to the groups fighter? — Django · 4428
The enemy can't engage you until the end of your turn, if that means the investigation phase (as I would assume), then they can still engage you and attack you during the enemy phase. Makes it less useful, especially for hunter enemies. Still seems pretty good in some cases though (Especially solo) — Zinjanthropus · 213
Also a good way to trigger a slew of succeed-by-two effects — Zinjanthropus · 213
3 exp to have the action of Stealth(0) fast. I already find Stealth(0) weak. I suppose it's better in solo. — Mataza · 17
Not requiring an action is a substantial upgrade — Chitinid · 14
I had my doubts about this card, but it has been amazing with Trish! It works very well with her ability. Essentially disengage an enemy without taking an action, then investigate your location, which when you succeed you can grab a second clue (cause the enemy is there), or exhaust the enemy if you want. I'm definitely a believer in this card now. The free action makes a world of difference. — lockque · 1
With Kymani, this card finally finds its permanent home — Amante · 4
Kymani and also Exploit Weakness — Zinjanthropus · 213

This card is going to have a second life with Kymani, the evader’s evader. The tricky thing is, this card isn’t for the first evade you do a round; it’s for the second. That one doesn’t matter if you exhaust an enemy, because they’re exhausted. Combined with the police whistle, it might feel that the grappling hook becomes secondary in many cases. (It really depends where clues are versus enemies on the board.) Still, a +2 and a free action for something you want to do almost every turn of the game in multiplayer, hard to beat.

(There’s also a combo using stealth on your nemesis weakness or the Guardian of the crystallizer, because those enemies won’t engage anyone else, even if you leave them in a room with three other investigators!)

MrGoldbee · 1315
I see no real value of the Riot Whistle in Kymani? They has (have?) any number of free engage built into their ability, as long as they are exhausted. Sure, they could engage enemies off other investigators or aloof ones, but that seems not enough value to me. — Susumu · 271
Depends on the team really, if they are primarily an enemy manager in group with 3 seekers, they will probably be taking an engage action most turns. If they are solo clearly it's all but useless. Most games will be somewhere between those two extremes — NarkasisBroon · 10
Many of the people that you want to discard but can’t kill are aloof. The best example is probably silver twilight lodge members. — MrGoldbee · 1315
Fair, that sounds like sick deck tec for "For the Greater Good". I can see now including the Whistle for certain scenarios with Adaptable. But I think in most cases, Kymani will have better cards in that slot. — Susumu · 271
I think both opinion are good. That's your preference, and I think either is not bad. — elkeinkrad · 409
Here, I add one more opinion. Kymani could evade any enemy in their location using Breaking and Entering; then, they can engage for free. Morever, Breaking and Entering (2) will be released, so that they can play it for each round. — elkeinkrad · 409
Enemies exhaust after they attack you during the enemy phase, so you can actually use this as Kymani to kill them for 0 actions in the enemy phase, though you eat an attack for doing so. — belphagor · 7
The fast trigger for Stealth (3) only works during an investigator's turn so you can't activate it during the enemy phase, except through Honed Instinct (with the taking damage/horror trigger) shenenigans, and I'm not sure if that works because the true meaning of "as if" still eludes me. — koaexe · 12