Rising Tide

My take on this set: This set provides escalation and some payoff for the flooding mechanic that is used in several Innsmouth scenarios. Two of the six cards act as accelerants, causing some early and unpredictable floodings. The other two provide the usual effects that you’d expect from treacheries (damage, horror, discard), but only at flooded locations.
The intention is punishing players for standing in flooded spots while drawing these, but i am not convinced they actually meet that goal. Due to surging when drawn at non-flooded locations, the player is going to be hit by something either way and especially with Undertow there’s a good chance that the next encounter card is actually worse than the original draw. Arguably, someone with high agility should end their turn in a flooded location to stop these cards from surging into something they can’t handle with just a test … which is a bit weird.
Rising Tides provides a bit of variance to the speed at which the flood progresses which is good. But at least during Pit of Despair this card is completely dwarfed by the flooding that happens from the agenda cards. In Too Deep supplements the flooding from Rising Tides with two more cards from the Syzygy set, which helps a lot with making the flood mechanic be more dynamic and unpredictable at lower player counts.

What it does: The nearest viable location has its flood level increased. If no location is able to be flooded further, Rising Tides surges.

My take: I am surprised to see only two of these in the set. Its effect is fairly straightforward, every time this card is drawn the flood level goes up somewhere. While this has no immediate consequence, it provides the condition for other cards to do their thing. That includes the other four cards from this set, but most importantly it enables scenario specific effects like the drowning damage on Pit of Despair’s agenda.

Threat level: Scenario dependent. By itself, the rising flood doesn’t do anything. But depending on what effects play off of it, the stock of this card goes up and down. So while it’s a very minor card in Pit of Despair (where the agenda flooding overshadows this card massively), it’s a big threat in Light in the Fog where players are tasked with keeping the flood away from certain locations.

Dealing with it: This isn’t really something to specifically deal with, it’s more an extension of the scenario rules.

What it does: If at a flooded location, Undertow is put into a players threat area. It stays there until they either spend a card from their hand and pass a fight or agility test or until they move. If discarded by moving, Undertow deals 2 damage and 2 horror to that investigator. If drawn by an investigator at an unflooded location, Undertow simply surges into the next encounter card.

My take: Two damage and horror is quite a lot, luckily it’s delayed and can be avoided by discarding a card and passing a test. The test itself isn’t terribly hard, having a choice between two different skills makes it more accessible as well. It also doesn’t take an action, as long as the player doesn’t run out of cards they can keep retrying the test. Only some investigators that lack either skill (Harvey, for example) may need help from another player if they can not afford taking the damage and horror on the chin.

Threat level: Medium. The effect itself is punishing enough, but most investigators should at least have a fair chance of avoiding it.

Dealing with it: Not taking up any actions is a godsend here. Often this will end up just discarding a card or two, a perfectly fine result from an encounter card considering that the discard isn’t even random. Not taking any actions also means that getting rid of Undertow won’t provoke any attacks of opportunity from engaged enemies, meaning that there is no reason to have it stick around for long.

What it does: Like Undertow, Riptide only has an effect when the investigator is at a flooded location, surging otherwise. Riptide has the player make an agility test against a difficulty of 3 or 4, dependent on the current flood level. After failing the player has to discard one of their assets. If no assets can be discarded, they will have to discard a card for each point they failed by instead.

My take: As far as treacheries that attack assets go, this is a mild one. It only works on flooded locations and it does allow a saving throw unlike some others. It also allows players to discard something of their choice instead of going for the most expensive one as some cards from other campaigns (for example Threads of Reality) do.
This sort of card is usually most impactful during the first few turns when players may only have one key asset in play, like the classic round 2 “Crypt Chill vs. Leo de Luca” situation. This is when Riptide’s restriction to flooded locations will often cause it to surge instead. This defangs the card severely.

Threat level: Medium. Losing assets and their associated actions and resources spent on them always stings. But compared to other cards of its ilk, this one has several conditions keeping it from being too punishing.

Dealing with it: Anything said about previous asset destruction treacheries applies here as well. Having some cheap sacrificial asset like a Scroll of Secrets or a Fine Clothes will keep the impact of this card low and protect your more valuable allies, weapons and spells.