I do not fully understand how does (the 2nd option of) the ability on Trish Scarborough (The Innsmouth Conspiracy #3) work.

It is a reaction: After you discover 1 or more clues at a location with an enemy: ... or automatically evade that enemy...

For this evasion to work, Trish has to be engaged with an enemy, right? So if she takes an Investigate Action or plays an event that allows her to discover a clue, it will provoke the enemy for an attack of opportunity first. I don't know how useful that will be.

But in the game play video from FFG on Oct. 15, Trish went to the location where Evan has an engaged enemy, and after Trish investigated and got a clue, she allowed Evan to evade that enemy. If this is legal then Trish's ability is useful. But is this move legal?

9 minutes ago, Angus Lee said:

For this evasion to work, Trish has to be engaged with an enemy, right?

To take the Evade action Trish must be engaged with the enemy, but you can evade an enemy (meaning exhaust it and disengage from it) without needing to be engaged with it yourself. It is confusing because "evade" is used for both the name of the action and to describe effect that it produces.

Trish's ability is producing the evade effect rather than granting an evade action so, like the free triggered ability on Stray Cat, it can be used on any enemy at her location regardless of whether she is engaged with it or not.

15 hours ago, Angus Lee said:

I do not fully understand how does (the 2nd option of) the ability on Trish Scarborough (The Innsmouth Conspiracy #3) work.

It is a reaction: After you discover 1 or more clues at a location with an enemy: ... or automatically evade that enemy...

For this evasion to work, Trish has to be engaged with an enemy, right? So if she takes an Investigate Action or plays an event that allows her to discover a clue, it will provoke the enemy for an attack of opportunity first. I don't know how useful that will be.

But in the game play video from FFG on Oct. 15, Trish went to the location where Evan has an engaged enemy, and after Trish investigated and got a clue, she allowed Evan to evade that enemy. If this is legal then Trish's ability is useful. But is this move legal?

The ritual asset Obfuscation is fantastic for Trish. If she is engaged with an enemy, she can investigate, cancel the AoO and still evade the enemy with one action.
With the above example, Investigator abilities sometimes circumvent the normal rules. For example William can play an asset from his discard pile after defeating an enemy, with no extra action. Certainly not legal for anyone else! So the example of Trish discovering a clue and automatically evading an enemy engaged with a different investigator at her location, is allowed by her ability, since it says she can “automatically evade an enemy at her location” There is no stipulation as to who an enemy has to be engaged with or if it needs to be engaged at all. She can even evade an aloof enemy without taking an action, in that circumstance or an elite enemy, since there is nothing stating otherwise.
Her ability is also written in a way that means it doesn’t have to trigger on the heels of a successful investigation. It just says “after you discover one or more clues at your location...” There are both Seeker and Rogue cards that let you discover clues without a test. Working a Hunch is great because it’s fast, so even if you are engaged with an enemy, you can discover a clue without an attack of opportunity, and automatically evade that enemy without even taking an action! Intel Report lets you discover clues without a test by buying them. Extensive a Research let’s you discover two clues at your location, although you have to have a lot of cards in your hand for it to be cost effective (unless you are having one of those scenarios where you are rolling in resources with no way to spend them). If you aren’t playing Taboo, Trish can have Pendant of the Queen which allows you to discover a clue without taking an action as well. Art Student and Lola Santiago can also discover clues with out a test.

Thanks Assussanni and Mimi61 for the replies. I am clearly understand the ability now. I have the confusion because the card text I read is "automatically evade that enemy. (full stop, without 'at her location')". If the card reads evade that enemy at her location (just like the wordings of Stray Cat), I would probably understand that it can be used to evade an enemy not engaged with her.

5 hours ago, Mimi61 said:

If you aren’t playing Taboo, Trish can have Pendant of the Queen …

She still can. The „chained“ XP only increases the cost but not the level of a card.

Narrow Escape is also great card for Trish too for the same reasons Mimi pointed out for Obfuscation.

I'm definitely packing Obfuscation x2 in my 19XP Trish deck that I just put together. I'm grateful for this thread, because I was a little fuzzy on the OP question myself. I re-read the Trish chapter in Investigators of Arkham Horror last night, and I'm psyched to play her.

She's alot of fun and there's plenty of tools to make her ability fire without an AOO in the box. Obfuscation being top of the list. That's such a nice card for her. Also Cryptographic Cipher has been real useful. Between the two I had alot of freedom to avoid the AOO and still get the evade if the rest of the team couldn't get the enemy off her first.

I've had less success with Eavesdrop, which should be a great card in her deck. My problem with it and why I eventually cut it is that in Seeker she has alot more less conditional ways to get clue acceleration. It always felt like the least valuable clue card. Though it's super flavorful which makes me want to put it back in and take something else out instead to force myself to use it. Likewise Followed feels like a bomb card in some scenarios, but often it's sitting in my hand due to it's restrictive nature which is interesting. In true solo having enemies following you around is probably going to be more of a consistent thing than in higher player counts where someone is usually itching to kill stuff. I do like that that archtype is in play now and potentially will get more support this cycle. Also all them snakes in TFA. This would be an interesting build to play in that cycle.

I did take Followed x2.

I lucked out in my Basic Weaknesses for Trish--they are all enemies! Although I'm not really looking forward to Accursed Follower.

13 hours ago, phillos said:

She's alot of fun and there's plenty of tools to make her ability fire without an AOO in the box. Obfuscation being top of the list. That's such a nice card for her. Also Cryptographic Cipher has been real useful. Between the two I had alot of freedom to avoid the AOO and still get the evade if the rest of the team couldn't get the enemy off her first.

I've had less success with Eavesdrop, which should be a great card in her deck.

That's interesting, because I've found almost the exact opposite. I've even gotten Obfuscation in play a few times but never actually triggered it (though it is a 4-player game, so plenty of opportunity for our Guardians to pull things). Eavesdrop, on the other hand, may be slightly conditional but opens up a second option for getting clues - it's still a test, but against a different target number. So I tend to make use of whatever is easier. Low evade value but high shroud? Evade then Eavesdrop for three clues. Low shroud but high evade? Investigate, take the free evade. High everything? Slip Away is just as good with her as it is with Finn, so you've got a reliable evade that becomes a free action if you hit the investigate.