Soloclue covered the best uses for Glimmer, but I want to talk about its individual effectiveness when those synergies aren't available.

The first thing to note is that all symbols aren't equal. Depending on the makeup of the chaos bag, being 1- or 2-over the threshold can have drastically different odds of success. Meanwhile, being 3-over won't improve your odds at all if there are no -3s in the bag. In a lot of cases, committing a +1 to three tests is much more useful than committing a +3 to one test. It lets you sit at a comfortable chance of success and avoid the many "-2, if you fail do X" penalties for drawing symbols.

Glimmer of Hope's utility is in ensuring you—and your fellow investigators—hit that comfortable target as efficiently as possible. As a recurring +X to tests, it's comparable to a pump asset like Dig Deep, with a few advantages (and limitations). While pump assets cost two dollars and an action to install them up front, Glimmer can be played out of hand and is paid for only when you need to recur it. If you draw a Glimmer in the upkeep phase and immediately need to use it, that's fine. Glimmer is also a wild symbol, whereas pump assets only affect two skills—and in survivor, neither available pump asset affects . And while pump assets can only boost your own skills, Glimmers can be tossed around to other investigators' tests.

However, Glimmer suffers in a few ways. Most glaringly, their usefulness depends on how many you've drawn; recurring a single for a dollar and an action is a terrible exchange rate. Drawing two breaks even, but ideally you want all three; without heavy card draw, that can be difficult. Also, the cost of an action and a dollar isn't quite the same as two dollars for the equivalent boost from a pump asset. Depending on your economy you may find yourself with an excess of cash, especially late in a scenario, but you will rarely have an excess of actions. And finally, while a pump asset can hit any threshold(s) with enough cash, Glimmer has a hard limit of +3 to a single test. There's no way to bank more, and recurring the +3 for a second test provokes opportunity attacks.

So is it good? As established, with Pete/Wendy/Minh or a Cornered deck, it's great. With a lot of card draw or a scenario where you expect discard effects (e.g. Dunwich), its good. Silas runs cheap and focuses on combat, so he generally prefers Scrapper/Scrapper. Preston hates it. With anyone else, it's really down to preference, with a slight edge if you're playing multiplayer.

I'm going to give this a try in Patrice Hathaway. It's a cheap spell she can get out that helps her deal with Watcher from Another Dimension. Plus, you get extra actions. I really really like extra actions to deal with hidden weaknesses / weaknesses / playing the things in your hand.

I'm also going to give this a try in Leo Anderson. Leo's lack of innate evasion where sometimes it is required makes this kinda a really interesting choice. HMMM. What a weird investigator.... uses Willpower from Guardian statline on a Rogue/Mystic card that lets you use agility, but Leo takes advantage of the card pool access...

This event seems absolutely fantastic for Rita Young. An attack at skill value 8 is nearly guaranteed to succeed on standard against all but the strongest of enemies. And the auto evade afterwards means you can ping the enemy for a third point of damage or move for free! Not bad for 1 resource and 1 experience.

Also pretty good for Nathaniel Cho. It's a Spirit event, so he can look for it with his Boxing Gloves. There is a lot of competition for card slots in his deck tho.

This would be the fourth card that Parallel Daisy back has access to that Standard Daisy does not, the other three being Grimm' Fairy Tales, Scroll of Secrets (3) (Mystic), and Book of Shadows (3).

Of those three, Book of Shadows is by far the most interesting. Parallel Daisy back has access to the Archaic Glyphs spells, which use charges, rather than secrets (and so can't be recharged with Astounding Revelation). Book of Shadows could conceivably guarantee a use of Guiding Stones every turn, which is pretty strong. Where this starts to get really exciting, in my opinion, is with the Astronomical Atlas. Combining the extra icons + recursion from the Atlas with Practice Makes Perfect and you're well on your way to big commit Daisy deck that can just scoop up mountains of clues very consistently on higher player counts.

There are 3 tomes that Parallel Daisy back has access to that Standard Daisy back does not: Grimm's Fairy Tales, Scroll of Prophecy (3) (Mystic), and Book of Shadows (3). Of those three, Book of Shadows is by far the most interesting. Parallel Daisy back has access to the Archaic Glyphs spells, which use charges, rather than secrets (and so can't be recharged with Astounding Revelation). Book of Shadows could conceivably guarantee a use of Guiding Stones every turn, which is pretty strong. Where this starts to get really exciting, in my opinion, is with the upcoming Astronomical Atlas, which allows you to commit the top card of your deck to a skill test and add it to your hand if you succeed. Add in Practice Makes Perfect and you're well on your way to big commit Daisy deck that can just scoop up mountains of clues very consistently on higher player counts.