Probably the best Investigator in the game to use this card would be Wendy Adams. Wendy's Amulet allows her to recur events from the discard pile. Due to the wording of her amulet, Events that end up attaching to locations do not end up going to the discard pile (and, therefore, do not end up going to the bottom of her deck).

When Hiding Spot would expire at the End of the Enemy Phase as a result of a ready enemy being at an attached location, Hiding Spot would be discarded straight to the top of the discard pile. There's a Player Action window at the start of the Upkeep Phase that allows Wendy to use the Amulet's ability to play Hiding Spot out again to a location.

Unfortunately, that small gap in time allows any enemies at a location to immediately engage with any Investigators there (and playing Hiding Spot does not cause them to dis-engage, they just gain Aloof). However, playing Hiding Spot to the same location will help keep out MORE enemies drawn from the Encounter Deck, while your team deals with the enemies currently on them.

At first glance, Uncage the Soul seems to be a great 0-cost card able to lower the cost of any Spell or Ritual by a substantial 3 resources. A closer look reveals that its usefulness varies depending on whether the spell/ritual played with it is an asset or an event.

For spell assets, Uncage the Soul appears to live up to its promise. With 1 action (i.e., the play of Uncage the Soul) you can play a spell asset from your hand and reduce its cost by 3 (to an unstated minimum of 0). This saves an action over playing Emergency Cache then that spell. Also, as a cost reduction rather than a resource gain, it bypasses any effects that may prevent you from gaining resources. Another benefit over Emergency Cache is that, if drawn late in the game when you may not need its resource acceleration, Uncage the Soul can be used for its substantial 2 icons, while Emergency Cache would be a dead draw.

On the downside, unlike resources from Emergency Cache, Uncage the Soul is limited to Spells and Rituals, but this shouldn't be a problem for most Mystics . Also, whereas you would still have 1 resource left over if you used Emergency Cache to play a 2-cost spell like Clarity of Mind, Uncage the Soul won't give you a refund if the spell played costs less than 3 resources. So, to maximize its potential, you will want to use Uncage the Soul with spell assets costing 3 or more. Currently (as of The Path to Carcosa), the only such spells are Shrivelling and Rite of Seeking, in their various versions.

For spell events, the effectiveness of Uncage the Soul is hit-or-miss. This is largely because Uncage the Soul itself does not have the Fast keyword, nor is its effect a action. So, using it to play a Fast spell will still cost you an action, making it no faster than using Emergency Cache [though, Uncage the Soul may still be preferable to Emergency Cache for its skill icons]. It also means that using it to play a spell--like Blinding Light or Bind Monster--while you're engaged with an enemy will trigger an attack of opportunity before that spell resolves. Play of Uncage the Soul is also limited to the Investigation Phase, so it can't be used for cards typically played in other phases, like Hypnotic Gaze which would usually be played in the Enemy Phase, or Marie Lambeau's Mystifying Song which would normally be played in the Mythos Phase.

So what spell events does that leave us that can benefit from Uncage the Soul? Basically, any non-Fast spell event played in the Investigation Phase while unengaged, and preferably costing 3 or more resources. Soooo... Astral Travel, or maybe Agnes Baker's Dark Memory weakness. Lastly, using Uncage the Soul with Sefina Rousseau's The Painted World (which itself is a spell) raises the question of whether it would lower the cost of a non-spell event copied by The Painted World. I think the answer to that is "no" because The Painted World doesn't have a cost until it becomes an exact copy of the event it's representing, at which point it is that event for all intents and purposes. So if that event is not a spell, Uncage the Soul won't reduce its cost.

In general, Uncage the Soul seems to be less useful than first hoped. For Mystics or other spell-casters with expensive spell assets--namely Shrivelling and Rite of Seeking--in their deck, it is a good replacement for (or addition to) Emergency Cache or other resource acceleration for Uncage the Soul's action advantage and 2 icons. Since the pool of pricey spell assets is only likely to grow with future releases, Uncage the Soul should become more useful over time. On the other hand, its usefulness with most spell events seems limited. Though that spell pool--and presumably Uncage the Soul's usefulness--should grow over time as well. Or maybe we'll get an experienced version that makes Uncage the Soul more like what I had hoped for--a seamless action advantage and cost reduction for any Spell or Ritual. Perhaps something like: "Fast. Play immediately before you play a Spell or Ritual from your hand to reduce its resource cost by 3."

In the case of the token, if there are currently no clue tokens on any Brood of Yog-Sothoth, one cannot choose the first option and consider the effect of the doom token done ; in this case one is compelled to choose the alternative (-4 in easy/normal, auto-fail in hard/expert).

Ruling by Matthew Newman here) :

If you are instructed that you “must” choose among multiple options, you are compelled to choose an option that has the potential to change the game state (Rules Reference, “Must,” page 16). In this case, if there are no clues on any Brood of Yog-Sothoths in play, you cannot choose that option, and must instead change the token’s modifier to –4.

Some observations:

Since the committed card gains after it's committed, this doesn't let you commit cards that don't a matching symbol or cards (like Emergency Cache) that don't have any skill symbols.

The effect only applied to skill cards, not any card you are using to support a skill check.

I always like cards that have multiple effects. For that reason (and more), I'm a fan of "I've had worse…". For 0-cost & no actions, it lets you cancel up to 5 damage/horror and gain that many resources.

Its first effect makes it a good upgrade from Dodge. Like Dodge, it is Fast and will work against Elite & non-Elite enemies alike. Unlike Dodge, which cancels all effects of an attack against any investigator at your location, "I've had worse…" only cancels damage/horror--not other effects that an enemy attack may have--dealt to you, not other investigators. However, "I've had worse…" can cancel damage/horror from other sources, like treacheries, locations, etc.--not just enemies. It also costs 1 less resource than Dodge and provides 1 additional icon. So, if not needed for its effects, it can provide 2 to those all-important treachery tests.

Its second effect provides resources for a class that currently (as of The Path to Carcosa) has few options other than Emergency Cache for resource generation. [Stand Together is another option, but is only effective in multi-player.] When used against an attack from an enemy that inflicts 2-damage & 2 horror (probably the most likely scenario), "I've had worse…" can provide 4 resources toward playing that Shotgun or Lightning Gun or for Dynamite Blast.

The big question: Is all this worth 4XP? In solo play, I would say "Yes, indeed!" In multi-player, I'm more likely to upgrade to Stand Together, which costs 1XP less, provides a similar 4 resources, as well as 4 cards, and needn't be held until facing a large enemy. In solo, though, this is often one of the first cards I'll upgrade to when playing a Guardian investigator--even Zoey Samaras--mostly because, when played wisely, it can give you a Fast influx of 4-5 resources to set up play of your big weapon. That said, you will want to hold "I've had worse…" until it can be used against an enemy (or other source of damage/horror) that maximizes its resource gain. But then, Guardians are usually seeking out danger.

So, in summation: 0-cost, Fast, 3 skill icons, cancels damage/horror, provides resources. What's not to like about "I've had worse…"? Its only real drawback is its high XP cost. But, given all it does, I'd say it's well worth it. Though, as they say, your mileage may differ.