In my opinion, most companion cards have the strongest permanent effects in game, so it's often hard decide which ones to include. However Leo is easily the best of the companions.

If you compare leo to Beat Cop or Cat Burglar, they basically save you actions. Beat cop allows you deal 1 damage as free action (which is like killing enemeis with 1 HP for free), while cat burglar allows you to disengage from all enemies (with no check) AND move to a connecting location (which is 2-x in 1 action). However they both have strong limitations. This is where leo shines, as you can use the extra action for anything, including the above mentioned things.

• Regarding hist cost. As he's a rogue card, the owner can use Burglary to gather ressources, if you draw him later in the game.
• Leo is unique (asterisk in front of his name), like Dr. Milan Christopher, so only 1 player can have him on the board at the same time. So if wendy and skids are part of the same game, only one of them can have leo in play. Here i'd recommend to replace him in skids deck with beat cop. Skid's character ability can compensate for the lack of leo.

The usefulness of this card is obvious, if you need that last clue, and there's a room full of enemies without hunter... Still, like most Seeker cards, slightly underwhelming and very situational. Might fit in some decks though!

At first glance, Leo looks like an automatic-include in every Rogue deck. His power, granting an extra action every turn, is a huge benefit. Unlike things like "Skids" O'Toole's ability, it costs nothing per turn, and unlike Daisy Walker, the action isn't restricted. That extra action is fantastic.

The thing is, so is his cost. Make no mistake, a card draw, an action to play, and 6 resources is big. He is the most expensive card in the Core Set. He only has one - so he's not that useful for skill checks. Even the upgraded Leo De Luca, with it's reduction in cost, he's still the (equal) most expensive card in the game.

So... is he worth using?

If you can get him out early and keep him through the game, Leo De Luca is a huge boon. He will, over time, repay that huge initial cost. I've had games where this card has been the entire margin of victory. When you're racing against the clock, he can be brilliant.

If you don't get him out early, though, he's a wasted card. Late in the game he's too expensive to be worth the investment. For example, 6 resources would pay for 3 additional turns with additional actions for "Skids" O'Toole, and you'd still be better off.

And so I find that I end up either taking 2 copies of him (and no other allies) - to try to draw him in setup or as a Mulligan, so I can get him played on the first turn - or I take none, and instead use other allies. It's very much a "Leo" or "Not Leo" strategy.

Rogues can also have access to Cat Burglar, which is excellent, and "Skids" O'Toole also has access to allies like Beat Cop. Both these cards are very good, and make Leo De Luca look like less of an automatic choice - and more of a considered one.

For characters with weaknesses that force them to travel to distant locations (e.g. Searching for Izzie or Smite the Wicked), this card could be invaluable. As the FAQs note, you can move to any revealed location with no enemies - rather than having to move location to location. This can get you to your weakness location - and back again - much more quickly.

2 copies for Jenny Barnes seems an obvious choice.

Just an opinion.

What I like: There is not enough healing in the core set, so often times when you get low on health or sanity, you better book it or pray. The cost is reasonable, it doesn’t take up a slot, and you can use it on other investigators which could turn you into a little mini-healer which Agnes will love so she can ping a couple more times. The fact that it heals horror and damage is functionally useful. The will skill icon is great for both Roland and Skids right now, as they don’t have a very fun time with will based treacheries. Not needing a skill check to complete (medical texts) or a check to make it better (liquid courage) is also good in some situations.

What I don’t like: The action economy with this is abysmal. I understand, you’re not winning if you’re dying, but to just use it once you’ve spent two actions not making progress. I never feel like I have enough time to play it in solo, and even in multiplayer either the threats have been tackled evenly so there isn’t a dire need for it over something else or the situation is already so bad that spending those actions to recover won’t really help much. The scenarios are just too short in my eyes to warrant using this in most cases.

What it needs: Honestly, first aid needs more investigators like Agnes who care about taking some sort of damage or horror. It also needs other healing cards to stay out of the game. I would gladly take the risk on liquid courage over this, because healing two for a single action is much more reasonable even if it is only horror in that case. As time goes by I feel like healing options will only improve, and unless they are using first aid as a benchmark and everything else gets a risk or negative involved, first aid will fall to obscurity.

Scaling: Here’s where this card shines however. First Aid as it stands has the same level of power in all the difficulties, which gives it a slight edge. With no test needed to make it work and no test needed to get a benefit, it gets more reasonable as you up the difficulty. Easy and standard, I’m waiting for a better option but in hard and expert, this does seem a bit more reliable.