So, this guy confuses me. I've tried running a couple of builds for him both as solo and a supporting investigator but, alas, poor Yorick just doesn't seem to cut the mustard. He plays like a less-effective Guardian with a gimmick that doesn't synergise with the Survivor card pool and can't investigate at all. Compared with a true fighter he doesn't seem to be that good at actually killing things without focussing on that (at which point I might as well take Zoe with some Survivor cards) while his need for resources locks out a Dark Horse build. I really like the character background and would like to make him work but so far he's the worst in his class...Any suggestions?

Any suggestions?

A couple. Focus on the less obviously useful Guardian cards with single effects (like police badge). They stack well with his recursion. I generally go through build and burn phases with him, I build up assets on him (like lantern and shovel), then keep him dry on resources for cards like Dark Horse. Dark Horse, Lantern and Shovel have done right by me for investigating.

Think of him as combo recursion, and be ready to shift combos based on what you draw. For example, Police Badge, Red Gloved Man and Will to Survive is one of my favorites.

With Cherished Keepsake and Leather Coat, he becomes nearly impossible to kill. With Police Badge, he gains tons of bonus actions. With Beat Cop (preferably upgraded), he can dish out free damage all day. I played him through Dunwich with Daisy, and he made AMAZING use of Dr. Armitage's ability.

 

He fights just as well as a Guardian (same strength as Zoey and Roland, with access to the same base weapons, so I'm not sure why you think he's less effective). His ability is rock solid, tons of fun, and triggers all over the place. He has arguably the absolute best Elder Sign effect in the game, especially once you get some Will to Survive hijinks going on. The icing on the cake is that his signature card is fun and powerful, and his weakness isn't that bad, especially after he's set up a weapon.

 

He can't really investigate, so he's not great solo, but try him again as a fighty-role in a group with an eye towards building around his ability.

It's also worth noting that the Bauta mask from Carnivale is amazing for Yorick. He gains resources for recurring it and it helps him use his fight value for other skill checks.

I also expect he would have trouble soloing, but he can meaningfully contribute the investigations. His power is Flashlight friendly and Look what I Found is in faction along with some other choices.

 

One trick I have seen local players miss is that you should try to discard some of your initial setup. Eg. instead of playing the leather coat and just recycling it when its used up, discard it the first time for its icon then recycle it into play. 

 

The thing being that his power isn't just recycling, it's also action advantage by getting a free card play (and if used like this, a free test icon).

 

You may want to directly play a weapon to take down your first foe, and maybe a beat cop too, but most assets you play should go via the discard.

Ok, they're all fair points. My issue is perhaps more that I wanted to try out a Dark Horse-y Survivor and he's not that suited for it, which isn't his fault! I was running him instead of my normal beater (Zoey) and just found she seemed to be more naturally geared to kill, while having a few more options to pick up clues if she really needs to (Rite of Seeking is a beast). I guess I should try going again with a longer campaign and look at upgrades dedicated towards his ability. Armatige is a good shout too!

Dark Horse is wonderful in the right deck. I Dunwich'ed Ashcan  Pete with my main group and Dark Horse really kicked him up a notch. But it was also incompatible with some great cards, especially events eg "Look what I Found" and Will to Survive(3), even Lucky, became devalued by my desire to be near zero resources.

Yorrick is a massive resource consumer. Yorrick loves someone to have Charles Ross in play (much like all Guardians would) - or basically any way to have others help him out resource-wise. He can't afford to waste resource to enable Dark Horse.

Yorrick shines by rotating high-impact assets. Assets that were design to die. My invocation game had a high XP Yorric and he laughed at the big bad. He was unkillable by recycling leather coat and Cherished Keepsake, and could take down basically anything, by recycling Aquinnah(3) and Beat Cops(2). Calling in Favors is just ridiculous here, essentially fully recharging one of these while helping you find another.
We needed to take a little timing care, so that the beat cops tap-damage was usually a killing blow (maximizing the uses of Yorrick's power), but he was a machine.

I know 0XP Yorrick has some effectiveness issues, but the longer the campaign runs, the sillier he gets.

PS the lantern/shovel suck, machete and flashlight for the win.

If I use an asset with a skill icon committed to a Fight check that kills an enemy, can I play that card (paying its cost) to my play area?

If I use an asset with a skill icon committed to a Fight check that kills an enemy, can I play that card (paying its cost) to my play area?

No, the cards committed to the skill test only goes to the discard pile at the end of the test, i.e. after Yorick's ability would trigger.