After playing with this card for a while, there were some investigators that definitely had better uses with this card. Usually used in:

• Characters who can easily find Hyperphysical Shotcaster or recur it (= almost every ).
• Characters who would like some consistant fight/investigate option that their deckbuilding options doesn't support (= no , )
• Characters who can boost their primary stats through multiple ways

Notable examples that I found:

• "Ashcan" Pete: boost with St. Hubert's Key, Plucky. can use Duke to trigger Scavenging to recur Hyperphysical Shotcaster.
• William Yorick: boost with Beat Cop, Ace of Swords. Has innate recursion ability, can easily set up Scavenging with Short Supply + Yorick's ability
• Harvey Walters: boost with Dr. Milan Christopher or Whitton Greene, Death • XIII, Celaeno Fragments, Practice Makes Perfect. His innate draw engine allows him to find pieces more reliably.
• Rita Young: boost with Track Shoes, Peter Sylvestre, Fight or Flight. Has no access to rogue assets. Can recur Hyperphysical Shotcaster through Scavenging, and can get good burst damage with Dirty Fighting+Hyperphysical Shotcaster.

This is a very good card in multiplayer, 3 times. Or 2 if you pull the tentacle.

What characters can use this well (can buff intellect) and also can recharge this card?

Ursula can regain one charge with eldrich sophist and red clock, but that's expensive in xp and you can only have one clock in your entire deck (also hope you have both other cards available). She can also take Skeleton Key if you've got high shroud locations.

Akachi struggles to get enough intellect to use it well, but can easily recharge it with mystic cards, and starts with one extra charge.

Daisy has a tome that can add one charge per turn (one action for one charge isn't usually good, but she can ignore the action cost once per turn), but is usually too busy using tomes to investigate, and has already spent her resources.

When going for R3 Heretics doesn't end in the victory pile, meaning are still 0 but you won't earn any xp from them.

A quick houserule would be considering Heretics under the act as if they were in the victory display.One could also count those under Erynn for the in order to spice things a little.

This card may interact very interestingly with the sorta newly added card Burn After Reading with the latest taboo. Since the cost to re-aquire the card now is 0 but the card still is considered level two for any other purpose this card can now make the doom removal of Burn After Reading possible without spending other xp than the one on Burn After Reading.

It probably wont create huge ripples in and of itself, but it may lead to exile decks using Burn After Reading coming online a bit earlier or making the cost of the combo a lot cheaper xp-wise.

Funnily enough, the best investigator to place this on might be another Guardian.

It can move damage and horror from any card. That means it can heal your beat cops, guard dogs, Grete Wagner and Agency Backup forever as a free, 0 cost action. Infinite beat cops!

The icons are also fantastic for Well Prepared.

You need a very specific team composition to make this work but I have been loving playing Calvin Wright and playing this on my friend Leo Anderson. The ability to keep all those allies working forever is amazing.