Just looking at the numbers--1 resource for 2 Health & 2 Sanity--Dr. William T. Maleson has the best cost-to-stat ratio of any ally currently in the game (as of The Path to Carcosa). Though he is unlikely to unseat his tenured colleague Dr. Milan Christopher, he is still a good choice as a second ally with Charisma; as a cheap, effective damage/horror sponge; as a target for effects that discard assets; or for investigators for whom Dr. Christopher's resource generation is not crucial.

Once per turn, his effect lets you cancel an encounter card at the cost of 1 clue. The good news: His effect is a reaction, so it doesn't cost you an action; being reactive, you can decide whether to use his effect after you've drawn the encounter card; it cancels that troublesome encounter card; and the clue paid to do so is placed on your location, so it can be picked up again with Roland Banks' effect, etc. The not-so-good news: This effect only works for encounter cards you--not other investigators--draw; the canceled encounter card is shuffled back into the encounter deck, not discarded; and a new encounter card still has to be faced. So, basically, unless you're using some sort of scrying, you've chosen what lurks behind curtain #2 to buy a reprieve against what's revealed behind curtain #1.

Is this effect worth it? That largely depends on how bad the avoided encounter was (compared to the new one drawn) and whether you needed that clue (and, if so, how effectively & quickly you can re-discover it). Maybe that was your only clue, so your Survivor investigator can use Newspaper to easily scoop it back up. Or, perhaps your Seeker investigator is keeping extra clues on himself/herself for "I've got a plan!" or Rex's Search for the Truth, so can drop one without slowing the pace of the game. In any case, you're likely to use Dr. Maleson's effect on an "as-needed" basis rather than every turn, as opposed to other allies whose effect you might use each turn.

There's another use for Dr. Maleson's effect, though. Being able to put a clue back on a location with no clues can benefit several cards, including Roland Banks, Roland's .38 Special, Cover Up, Inquiring Mind, Preposterous Sketches, etc. Dropping a clue on a location in order to get that extra +2 from Roland's .38 Special or to use the 3 icons from Inquiring Mind can make the difference between success & failure. And, since Roland's Core signature weakness, Cover Up, only works on clues as they are discovered, dropping one and re-discovering it in order to remove a clue from Cover Up can potentially save Roland some mental trauma. [I've actually encountered all three of the above situations when playing Roland.] [EDIT: A couple upcoming cards--Forewarned & Mysteries Remain (a spoiled alternate signature card for Roland)--also enable you to drop a clue at your location, perhaps indicating that more cards may use this mechanic.]

From the above, you can probably tell that I think Dr. William T. Maleson is a good fit for Roland Banks, for both his effect and as a cheap horror sponge. His effect may not edge out the first-choice Beat Cop or Art Student for Roland, or Dr. Milan Christopher for Seekers, but his super-low cost & good stats alone make Dr. William T. Maleson a good fit for any investigator that has a deck slot for him.

Here's hoping FFG releases an experienced version (or two) of Dr. Maleson (Working on Something Even Bigger/Truly Huge), perhaps with his effect upgraded to discard rather than shuffle the canceled encounter card and/or to allow his effect to target any investigator at his location.

Maleson is most useful for investigators that have EXTREMELY lopsided ability to deal with certain encounter cards over others, so that it's actually worth dropping a clue in order to swap a "ruinous" encounter for a chance to draw a "breezy" one. It also helps if the investigator is likely to have clues to spare, and can pick them back up in a hurry.

Therefore, Maleson is suited to two investigators in particular:

Minh Thi Phan:

• uniquely vulnerable to Enemy cards:
  • 2 Combat;
  • 2 Agility; and
  • no Mystic cards to weaponize her Willpower;
• strong against Treachery:
  • 4 Willpower;
  • crazy skill card combos.

Finn Edwards:

• uniquely vulnerable to many Treachery cards:
  • 1 Willpower;
  • One. Willpower.
• strong against Enemies:
  • 4 Agility;
  • free Evade action, and;
  • some decent weapons and attacks.

Crucially, they both also have the four Intellect they need to pick their clue back up from most locations with reasonable odds.

Ultimately Maleson is a stronger choice for Finn. Minh Thi Phan will usually do better with Dr. Milan Christopher, and a well placed Level 2 Shortcut will let help other investigators come to her rescue more efficiently in addition to its other benefits. Her special ability also means she'll be sharing space with other investigators a lot, so she can often just foist her Enemy encounters on whoever is nearby. Conversely, rescuing Finn from a Treachery card isn't even possible for a lot of fellow investigators, so giving him the ability to mulligan the cards himself can change a scenario-breaking debacle into an inconvenience.

I might even consider including it over Leo De Luca for Finn, because it's one of the game's few repeatable cards that protects against encounter-draws. Between Maleson's ability as a first line of defense, "You handle this one!" as a second, and Maleson's damage-soak as a third, Finn can largely insulate himself from his main weakness, and thereby dedicate his remaining 26 cards to grabbing clues and murdering or exhausting enemies.

Of course, Leo may also be too good to pass up. Charisma may be in order!

Edit: I'm actually downgrading my assessment of Leo De Luca (see my review there for an explanation), so Dr. Milan Christopher is the more relevant anchor comparison.

I'm sure this is obvious to experienced players, but as a pretty new player, I've benefitted from reviews that explain synergies and changes from newer cards, so I thought I'd add a little one here:

The Ally slot math is different since the release of Miskatonic Archaeology Funding, at least for Seekers. The 4xp permanent which lets you slot 2 additional allies with the Miskatonic trait.

That's two XP less than taking double Charisma, and usually doable after the first scenario. Go ahead, put three different level zero allies in your deck. They will only be dead draws during the easiest scenario in your game. Now you can have your cake and eat it, too.

Well, you can eat most of your cake, anyway. Slowly. The Funding restricts you to dealing one damage or horror to a Miskatonic ally per blow you are taking. This reduces his effective soak potential to 3, over three separate hits. Still a bargain! But bring along someone not funded by Miskatonic, or another soak, so that you have somewhere else to spread out the heavy damage hits.