For Agnes, this card can be even better than simply canceling an attack. When you are up against a big baddie, she can choose whether to cancel their attack or allow 1 horror to go through in order to return 1 damage to them.

If you want the Friends Forever achievement for Edge of the Earth, play Mark Harrigan and take this lady along for every scenario. You’ll be absolutely unstoppable, since she synergizes perfectly with Sophie. That’s not to say she isn’t also an incredible asset for many of your Guardian allies either. Beat Cop, Guard Dog and Grete Wagner are all great examples of cards who will benefit greatly from her ability. Since you’re likely playing guardian cards if you’re bringing along Dr. Mala, feel free to pack a copy or two of Inspiring Presence for emergencies.

Parallel Pete dropped a few days ago. He doesn't seem to be getting a challenge scenario so I might as well vent my thoughts here.

First off, the new signature, Pete's Guitar, grants you unprecendented control over enemies. Exhaust it to force a non-elite enemy at your location or any connection location to move in a direction of your choice. It of course synergizes with the parallel front ability, allowing you to push enemies into Snare Traps, Makeshift Traps and whatnot. It can also indefinitely keep one non-Elite Hunter away (extremely useful in TFA and still much appreciated otherwise) and you get 1 buck or 1 horror heal each round for the trouble. You can pull a nasty monster away to give your cluever valuable time. For pesky Aloof enemies or Acolytes, you can force them to move towards your team's monster killer so that they can spend fewer actions on moving and more on killing. The possibilities are endless. This is a signature so good that it could seriously give Best Doggo a run for his money.

The downside is that Pete's weaknesses are also supercharged. Wracked by Nightmares disables both of Pete's signatures so it must be dealt with as soon as possible. The replacement weakness, Hard Times, forces you to choose and discard the same number of cards after you draw any number of cards. Occasionally this may work in your favor by getting the Improvised suite into your discard but I wouldn't rely on it. It is still a crippling weakness, perhaps a bit lower priority than Wracked by Nightmares. God helps you if you draw them back to back though.

Parallel Pete himself actually seems a bit bland when compared to his new toys though. For Parallel front, starting with Pete's Guitar is nice but the ability to recycle attached cards seems situational at best. Duke is still a great first turn asset and the ready asset ability would see a lot more play - you can also dig for Pete's Guitar then double-tap it to practically trivialize enemies until you feel like dealing with them. On the other hand, Parallel front has 7/7 health/sanity instead of 6/5 so he would be a bit bulkier if he could get Duke out early, especially with the horror heal from his Guitar. Parallel front also has 3 Fight instead of 2, but it is not enough for Pete to fight without other boosts. These differences overall do not feel significant enough to detract from the real choice - whether you want to start with the dog or the guitar.
For the back, you aren't losing a lot by going Parallel - as of TSK, there are a grand total of 8 Level 4+ Survivor cards (11 if you count the customizables), none of which seem particularly suited for Pete. The real tradeoff seems to be losing the 5 splash slots for access to Tactics 0-4 (all Improvised cards are anyway) and up to 5 Guardian level 0 cards. This feels kind of baffling - none of the off-class Tactics work particularly well with Pete's parallel front (for example, Ambush only works for enemies spawning so good luck getting it to trigger twice; "Fool me once..." has the encounter card attach to it and not the other way around so no recursion at all), and if you really like Guardian cards that much you could've taken them with your original splash slots anyway.

Overall, Parallel Pete feels like his actual investigator card is overshadowed by his replacement signatures. Quite a shame he doesn't have his own challenge scenario, but as FFG said, it is simply impossible to improve upon Duke, forever the best among all good boys. Also I think Advanced Wracked by Nightmares would give me a stroke so there's that too.

This card is a great example of Power creep, and why it prevents the use of newer cards.

This card is in direct competition to vicious blow, and begs the question "why would I ever use this over vicious blow?"

The short answer there is that you won't. Everyone that can take this card can also take vicious blow, and vicious blow outperforms this in all scenarios.

What about taking it AND vicious blow? I could see some use in the fighter style characters without access to the heavy hitting guardian weapons. Yorrick and Silas come to mind right away. But you still have to wait for this card to take effect, meaning the enemy will most likely get an attack off. This somewhat defeats the purpose of attacking the enemies then. Most enemies have 3 HP, and the ones that have more usually have 5-6. So you do a vicious blow augmented standard attack on a 5-6 HP enemy, and it lives and your turn ends. The enemy attacks you and then this ticks. So the enemy now has ~4 damage on them. This translates to you having to attack the enemy again your next turn to finish them off, or leaving them evaded for two turns someway to make this card eventually run its course. You very quickly then get into a Rube Goldberg style problem with "why didn't you just kill it with another attack", which begs the question again of why did you take this card.

So when do you use this card? The only reasonable excuse I could see would be on enemies with exactly 4 HP, using an investigator with smaller arms and probably that also has stunning blow and can outmove the hunter keyword.

It ends up being a lot of very specific criteria to make this card worthwhile, so I can't honestly say it has a place in any deck.

If future upgraded versions had a draw attached to it, we may be talking though.

It is important to note that placing doom on David is not mandatory and to maximise the profit from him it is best not to add doom every chance you get. A good rule of thumb is that you should choose to add doom a number of times equal to one-third of the remaining doom threshold on the current agenda when you play him (rounding to the nearest whole number) before using his ability with no doom until the witching hour. For example, if running David with Calling in Favors with a 6 doom agenda, you can maximise your resource gain in a single play of David by placing doom on him twice as follows:

-Turn 1: Place doom on David, gaining 1 resource. Mythos phase brings doom count to 2.

-Turn 2: Place doom on David, gaining 2 resources. Mythos phase brings doom count to 4

-Turn 3: Use David without placing doom, gaining 2 resources. Mythos phase brings doom count to 5.

-Turn 4: Witching hour so place doom on David, gaining 3 resources. Bring David back with Calling in Favors ready to replay for the next agenda.

This allows David to generate a total of 8 resources instead of the 6 you would gain if you placed doom on him on Turn 3. The effect is even more pronounced for agendas with higher doom thresholds, but the rule of thumb remains the same: place 1/3 of the remaining threshold at time of play.