Desperate Mark

"I came here to do two things: kill monsters and kick ass, and I'm more than willing to combine the two..."

Mark Harrigan, like a few other older investigators, got a recent buff with a few cards released in The Circle Undone. Namely, Act of Desperation, which lets Mark refund the cost of a weapon by throwing it at an enemy for increased damage, and .45 Thompson, the perfect card to throw at a monster's head. Even better, your first upgrades are absolutely two copies of .45 Thompson (3) so that you can start getting insane economy by doing what Mark does best. Pay 6 for Thompson, start shooting and getting paid, and then cash in your retirement when you're desperate.

Act of Desperation and Calling in Favors work quite similarly, letting you trade in a used up asset for a replacement. Emergency Cache is in the deck because Mark still struggles with economy until you've upgraded your thompsons. They're one of the first cards to go.

Scene of the Crime is OP.

"If it bleeds..." and Something Worth Fighting For are there to help soak/heal horror since his treachery can be pretty brutal. You also have plenty of allies.

Emergency Aid and Second Wind can help heal damage, and "Let me handle this!" combos a bit with Second Wind, giving you more chances to trigger the extra healing.