Rod of Animalism seems niche, and it is. It has two core flaws that make it challenging to play:
1) It's hard for it to pay for itself since you need to get it into play before you play your creatures. If you're playing enough creature allies to want it, odds are high that you end up drawing the creatures before you get the rod.
2) It's always in constant competition with Charisma. Yes, charisma costs two more xp for half as many ally slots, but it's a permanent, which guarantees you reliability, frees up a slot in your deck, takes no action to draw, resources to play, or actions to play. Those are all incredibly significant advantages for Charisma.
There are, however, a handful of investigators that can make it work.
William Yorick can make use of it in a creature-recursion deck making use of his ability to recycle cheap assets to let him search for clues with Mysterious Raven, evade with the Stray Cat, and kill enemies to keep endlessly recycling with the Guard Dog. In a Yorick creature deck, you're much more likely to be playing your allies over and over again, and having 0-cost items in your discard is incredibly valuable for Yorick. You are still likely better off with Charisma, so it's important to note that you are likely only aiming for the rod if you have other allies you are excited to play with Yorick, and there are plenty of amazing allies he has access to. Imagine a Yorick deck with Pete Sylvester as a horror soak in his main ally slot, a Mysterious Raven that can be endlessly recycled for testless, actionless clues with the raven's downside fully mitigated by Pete's endless resolve, that still has space for a beat cop or a story ally. Comboing Pete with the raven essentially means that Yorick has an ability that says "play Evidence for free every time you kill an enemy".
Daniela Reyes can make this card work for two reasons: she already has 3 incredible allies that she really wants to play with in Aquinnah, Pete Sylvester, and Jessica Hyde, which would already take two charismas to make work. At the same time, many of the available creature allies are uniquely good for her. Two guard dogs are absolutely essential for Daniela, as they work seamlessly with her ability. Unfortunately, the remaining creatures are somewhat lackluster for her. Miss Doyle could find a place with Augur to mitigate Daniela's 1 book. Here, it's not a case of Charisma vs. Rod of Animalism so much as a question of whether it's worth adding a Rod of Animalism on top of the two charismas you were already planning to have.
Charlie Kane loves allies, and will already be including double charismas as one of his first upgrades. Six allies is lovely, but eight is even better. Miss Doyle (whose accompanying cat does not take up an ally slot) is uniquely excellent in a Charlie deck, with all three cats potentially being useful depending on your build. Unfortunately, the Black Cat, isn't actually a creature, so you really need another animal or two to make it worth picking up. Could be excellent in the rare case when you pick up a creature story asset like Anyu, aka the only sled dog that isn't a trap, or in a monster-hunter build where you can actually make use of the improved guard dog. In a Charlie deck, the rod is probably never going to pay for itself; it's really just a way of getting even more allies.
Here's hoping they eventually create a Rod of Animalism(4) that becomes a permanent, Miskatonic Archeology Funding style, which would dramatically improve this card and make it a viable alternative to charisma for anyone who wants to include a few creatures in their deck instead of just for a handful of investigators.
