Pros:

• Has an resource, making it more useful for Captain Marvel and Iron Man.
• Flexible, being able to be used for anything a hero can exhaust for.
• No hero limit so can be stacked on a hero to thin your deck.
• Is an upgrade so can be set up ahead of time in case of emergency later.

Cons:

• Is an upgrade so needs to be set up before you actually know you will need it.
• Quite expensive at 4 effective cards (Tenacity + 2 resources + the resource).
• Requires a resource, which so far are not incentivised to be played apart from this card and Relentless Assault.
• Readying is an action (compare to Indomitable) so can only be performed during the hero phase, preventing Tenacity from allowing you to defend two or more times in one villain phase.
• Can't be used to recover twice in one phase.

The value of Tenacity is equal to the value of what exhausting a hero/Alter ego can do, so let's look at the best-case scenarios:

• Thwarting, which currently caps at 3 THW (more with lead from the front) with Captain Marvel or Iron Man and Heroic Intuition.
• Attacking, which currently caps at 4 ATK (again, more with lead from the front) with She-Hulk and Combat Training.
• Recovering, which currently caps at 5 REC with Jennifer Walters and the upcoming Kamala Khan
• Removing a couple of villain attachments, which is probably not something I would dedicate a deck slot to unless I was very concerned about a particular card.
• Ms Marvel's ability to return a card to her hand, which is difficult to evaluate currently.

So are any of these actions worth including Tenacity and paying 3 additional resources for? Potentially, if you are really worried about not having answers to an enemy or a sudden influx of threat in a future hand. This advantage is somewhat negated however by the need to have a specific resource in hand, meaning you might not be able to activate it when you want to. As such I think the strongest effect is potentially using it to recover as well as attack, thwart or defend in the same turn, as the amount of healing available through cards is quite limited at the moment.

At this point of the review, I have to acknowledge that I haven't played with Tenacity apart from the starter decks, where I'm pretty sure I just used the card as an resource. After this point, I removed it from my decks and haven't used it since, as it just looks way too expensive for what it does. Maybe I'm wrong about this, and it definitely has the potential to become more powerful if we see more powerful uses for exhausting a hero in the future.

The energy resource on Tenacity is actually a reason you might want to include it in a Captain Marvel or Iron Man deck in particular, but even for that I would prefer to include Haymaker or Emergency, which I will normally use for their resource but give me the option of preventing threat or dealing damaging if I really need to on that turn.

Verdict: Tenacity is a flexible card with a nice introductory readying effect that is simply overcosted for what it does. While I wouldn't currently include it in any of my decks, if readying becomes more powerful with certain heroes as more cards are released I will have to re-evaluate this.

This card, very plainly, is a piece of crap. Tenacity is known as one of the worst cards that is very well known, because it is in the core set. To start, it takes 3 ER (effective resources) to get out on the table, and then another specific resource () to activate once, get discarded, and ready your hero. To top it off, the art is just meh with a picture of Spider-Man fixing some buildings. I would erase this card's text, "Spend a resources...", and then I would probably still not use it, but it wouldn't be as bad. This card works well with Friction Resistance in Quicksilver's kit, but that is one card in a hero-specific kit. On MCDB most people only put this in decks with Quicksilver or Iron Man. I just like Stick-To-Itiveness (the 'Pool version) better.

Rating: (A+:C-) C