Effectively 2 stuns for the true cost of 5 (printed 4 + the card itself). As best as I can tell, in the existing card pool, this is one of the **least** efficient ways to prevent enemy attacks.

If we assume that you usually get 1.5 damage / 1 cost, we can try to evaluate the stun-specific cost of other cards like Superhuman Strength and Heroic Strike.

Superhuman Strength - **stun cost of 1.67**

- Cost of 2 (true cost of 3)
- Adds 2 damage to an attack. Assuming 1.5 dmg / 1 cost, the expected cost is 1.33
- True cost of 3 minus the 1.33 expected cost of damage leaves a balance 1.67 cost
- The card offers 1 stun, so we can assume the stun is costing us the entire remaining 1.67 cost

Heroic Strike - **stun cost of 0** (YES, ZERO!!)

- Cost of 3 (true cost of 4)
- Puts 6 damage on an enemy. Assuming 1.5 dmg / 1 cost, the expected cost is 4
- True cost of 4 minus the 4 expected cost of damage leaves a balance of 0 cost
- The stun actually costs you 0 additional cost above and beyond the expected cost of the damage!

Now, if we assume that an ally block and a stun are effectively the same (which they aren't exactly due to boost cards), we can pull in another data point like Mockingbird (who offers a stun AND a block).

Mockingbird - **stun/block cost of 1** each

- Cost of 3 (true cost of 4)
- At her most efficient she is thwarting instead of attacking - so we will assume a 1 thwart / 1 cost
- This puts her expected cost at 2
- True cost of 4 minus the 2 expected cost of thwarting leaves a balance of 2 cost
- The card offers 2 stuns (technically 1 stun and 1 block), so we can assume that each stun/block is costing us 1 each.

Going back to Webbed Up, it's clear that offering 2 stuns at a true cost of 5, or 2.5 cost per stun, is a poor trade off.

The final point to consider is that Webbed Up offers a *NEGATIVE* synergy with Spider-Man's *Spider-Sense* ability, by stopping the villain's attack **before** it is initiated.

**Edit: I was discussing with another player recently and they made the "negative synergy" point a lot more elegantly than I did:

- If you are playing multiplayer and prevent 1 attack on yourself, Webbed Up effectively costs you 6 cards (4 cost + the card + missing 1 Spider-Sense draws).
- Playing solo, you prevent 2 attacks, making the effect cost 7 cards (4 cost + the card + missing 2 Spider-Sense draws)!!