Consider you have an ally that does 2 damage with each attack and has 3 health. Fairly average. That ally will deal 6 damage total, over the course of 3 turns.
- If you heal that ally for 1 health, they are now dealing 8 damage over 4 turns.
- In this example, United We Stand has allowed you to spend 1 resource (itself) for 2 damage.
Now consider that you have three allies that deal 2 damage each and have 3 health. That's 18 damage total over 3 turns.
- If you play United We Stand during Stage 3 (Expert/Heroic), you will heal 1 damage from each ally. That means that they will now deal 24 damage over 4 turns.
- In this example, United We Stand has allowed you to spend 1 resource (itself) for 6 damage.
Either way you slice it, this card is pretty darn nuts. Also, keep in mind, you can use this on your identity and other player's and their allies. This is strong in all leadership decks, but I think it's at its strongest in an upgrade-centric leadership deck.
Notable drawbacks are that you must be an Avenger and in Hero form.