Note that the Passageway trait will trigger them too, and that they're hunting through passageways if at act 3. As such, it's recommended to have extra clues before going to the Hidden Library if you didn't get rid of them.

Finally, note they could have been much nastier though if the Halls shared a trait.

I think Dexter is the strongest Mystic investigator yet. His power gives +2 economy (including saving an action, the most precious commodity in AH) every time it's used, and it isn't too hard to set it up. He makes cards that are already strong even stronger (e.g. Arcane Initiate, David Renfield and Scroll of Prophecies, as well as the typical suite of spell assets), brings decent cards into the strong contender range (e.g. Forbidden Knowledge), and even makes a few obscure cards worth playing (like Alchemical Transmutation). The reason his power is so strong is the same reason why fast effects and cards are so good: saving an action and breaking the normal restrictions on play windows can be incredibly useful, especially on harder difficulties.

This card needs combo effects to be good. Namely, consider using this with Jacqueline Fine around, Olive McBride, or Dark Prophecy. Also Eldritch Inspiration can make the damage to the enemy go off twice. Canceling the attack and not getting the return damage on the enemy is a subpar effect for how expensive this card is, so you want to try to get the return damage every time.

Also worth noting that this works on Elites, so this can cause some big bads to hit themselves for a bunch of damage, which can be very useful.

As of the end of the Dream Eaters cycle, this is the only Rogue weapon that Preston can take. He probably doesn't really want or need it either since he'll be fighting at a 3, but hey, it could help you against rats?

This card is really good. Don't listen to the haters who say "if you want to support your fighter the stars need to align and you need to be together with them."

That's true most of the time, and when it isn't it's usually because they're coming to you--the enemy is in your face. That, or it's somewhere you both need to be.

For Daisy, Minh, Rex, Norman, and Ursula the 5 or more remaining sanity is rarely relevant. For Ursula and Rex it's even a decent trick just for defending yourself.

Pack it the next time you're running about at level 0. When your fighter lacks >+2 options for damage, this card is worth its weight in gold.