Aggression
Upgrade

Asgard. Weapon.

Cost: 1.
Resource:

Restricted.

Response: After your hero attacks an enemy, spend a resource → deal 2 damage to an enemy.

Thor #19.
Jarnbjorn
FAQs (taken from the official FAQ or FFG's responses to the official rules question form)

Q: Can I trigger Jarnbjorn after I play an Attack event?

A: Yes. A hero is considered to make an attack both through their basic attack power and actions with the (attack) label. -(Official FAQ)


Q: Will defeating an enemy with Jarnbjorn count as me defeating an enemy?

A: Upgrades are things your hero wears and wields, so when you use an upgrade to defeat a minion that count as your hero (or you) defeating that minion. -(Developer Ruling , Hall of Heroes)

Last updated
Reviews

The analysis provided detailing the cost-per-resource aspect of Jarnbjorn is an important thought process, but it does not detail the full value of the card as an upgrade.

One of the most important uses of Jarnbjorn's ability is that it provides an additional source of damage. Minions and Tough often require you to provide damage from more than one lane, and this provides a readily available source.

Further, should you build a physical resource heavy deck, Jarnbjorn will provide you an avenue to spend that extra resource you don't have use for this turn. As victory is decided by damage, it's always useful.

Judicator82 · 134
This is an excellent succinct review that I hope moves to the top of the page soon. The total damage / total cost analysis is not the way to look at this card. It is a small investment to unlock near perfect damaging efficiency the rest of the game. It is damage on-demand no matter what you've drawn for the turn, and at the ideal rate of 2 dmg/resource. Moreover, in the 3 years since review, we have more weapon synergies and make fist/wild resources the vast majority of our deck. An incredible card when built around — Stretch22 · 742

I think it's generally accepted that the average value for non-Hero card damage is around 1.5 damage/cost, with Hero cards reaching closer to the 2 damage/cost range.


Non-Hero Aspect Card Examples

Tac Team

  • Cost of 3 (true cost of 4) for 6 damage
  • 1.5 dmg / 1 cost

Uppercut

  • Cost of 3 (true cost of 4) for 5 damage
  • 1.25 dmg / 1 cost

Relentless Assault

  • Cost of 2 (true cost of 3) for 5 damage (minions only)
  • 1.67 dmg / 1 cost

Melee

  • Cost of 3 (true cost of 4) for 6 damage
  • 1.5 dmg / 1 cost

Hero Card Examples

Swinging Web Kick

  • Cost of 3 (true cost of 4) for 8 damage
  • 2 dmg / 1 cost

Supersonic Punch

  • Cost of 2 plus 1 to go Aerial (true cost of 4) for 8 damage
  • 2 dmg / 1 cost

Photonic Blast

  • Cost of 3 minus 1 for card draw (true cost of 3) for 5 damage
  • 1.67 dmg / cost

Getting back to Jarnbjorn, at the rate of 1.5 dmg / 1 cost you would need to get 6 uses out of Jarnbjorn to get average value. To get Photonic Blast type value (1.67 dmg / card) you would need to get to 10 uses. Any uses beyond 10 and you are approaching some of the best damage value in the game (but you'll never get to 2 dmg / 1 cost because of the initial 2 cost investment to play Jarnbjorn).

  • Cost of 1 (true cost of 2)

  • 1 use = 2 damage / total cost of 3

  • 2 uses = 4 dmg / 4 cost

  • 3 uses = 6 dmg / 5 cost

  • 4 uses = 8 dmg / 6 cost

  • 5 uses = 10 dmg / 7 cost

  • 6 uses = 12 dmg / 8 cost (1.5 dmg / 1 cost)

  • 7 uses = 14 dmg / 9 cost

  • 8 uses = 16 dmg / 10 cost

  • 9 uses = 18 dmg / 11 cost

  • 10 uses = 20 dmg / 12 cost (1.67 dmg / 1 cost)

Having to attack first limits it's utility a bit, but on the positive side it does thin your deck out and free up hand space (by being on the board).

Overall, a potentially strong card, but it needs a deck to be built around it. Getting into those double-digit uses will really allow for that positive return on your investment.

diesel · 164
An interesting analysis. Worth noting that recurring resources like Super Soldier Serum or Quincarrier significantly alter the math. — FreqKing · 25
I would add to your analysis the cost in cards of the card itself... — batman · 27
@freqking they do not alter this maths but they do make it very consistent. — Pickles · 32
@batman the card costs are included — Pickles · 32
You only get the full rate of return if your target actually absorbs all the damage. Occasionally you have to web kick a 6 hp minion or attack a Drone for more than one damage. Other times you are left with cards in hand you cannot spend. Jannbjorn largely removes that last inefficiency. You only have to spend one card via Jannbjorn that you would otherwise have stuck in your hand (or discarded) to tip the "1.5/resource" break even point to 3 uses. By doing damage in small chunks it minimises over killing things too and avoids retaliate, the bane of chip damage. — Pickles · 32
Triggering off of attack Events, and having no limit on how many times per round it can trigger, are big deals. Sweet little card. — Blackhaven · 12
Crazy good on captain america with his serums. — Blackhaven · 12

Here's what you need to know:

It triggers every time you attack and requires a might resource to deal damage.

QS has Friction Resistance which generates a might resource when exhausted, and readies every time QS does. QS can ready repeatedly every phase.

You can use Jarnbjorn (as long as you dedicate Friction Resistance to paying for it) every time QS attacks to add an extra 2 damage to ANY enemy in play. It far exceeds its cost almost immediately with QS.

MacGhille · 264
This isn't actually correct. Jarnbjorn never fully makes up its cost because to get anything out of it, you must constantly pay more into it. Each physical resource gets turned into two damage but the initial cost to play Jarnbjorn is never made up for. Unlike, for example, Combat Training which at some point does pay back its initial investment (typically six attacks depending on how you choose to value resources for damage) and then start turning a "profit" as you continue to attack and gain value at no additional cost. — Erathis · 17
That is a truly insightful point, and as soon as I started reading your comment, I could see that you were correct, mathematically. I personally consider Friction Resistance on Quicksilver to be a 'free upkeep' for Jarnbjorn. But that's not an accurate perception, and you have made me more cognizant of that. I do, however, consider the malleability of Jarnbjorn's damage application to be a 'soft benefit' that isn't easily quantified by the mechanics of the game. But I still stand by the basic concept that Jarnbjorn delivers value beyond its cost. Sure, you never truly break even with resources, but the benefits I feel make up for that. — MacGhille · 264
This actually becomes closer to fully efficient if you play with Hulk bc his hand must be discarded in hero form so those are effectively zero cost cards for Hulk. — FluffDaddy · 53