
A simple card, but a highly effective one for multiplayer Guardians. You spend one action, and the team essentially nets +3 cards and +4 resources in exchange (remembering here that Stand Together is itself a card you're giving up). That's pretty awesome. Compare Emergency Cache II, where you spend an action for essentially +0 cards and +3 resources. Or Cryptic Research, where you spend zero actions for +2 cards. Now, both those cards beat Stand Together in terms of flexibility (since you can play them when you're alone, or in the case of Cryptic Research even when you're engaged with an enemy), but in terms of efficiency, Stand Together just crushes both of them.
Stand Together shines the brightest when played Turn 1. Lots of investigators have multi-card setups that cost 6-7 resources, and Stand Together facilitates that. Zoey and Roland want to play Machete and Beat Cop (7 resources). Daisy wants Old Book of Lore and Dr. Milan Christopher (7 resources). Wendy wants Fire Axe and Leo De Luca (7 resources). Agnes wants Shrivelling and Peter Sylvestre (6 resources). Stand Together is just perfect here. It not only gives investigators higher odds of drawing these key assets, but it lets them get them all into play right away without having to use the inefficient "take a resource" action. This really gets things off to a roaring start.
Stand Together will of course still be good if drawn later in the game. It also offers double Will icons to be used in an emergency. Obviously, playing it for the event is better, but that's another nice little benefit over something like Emergency Cache.
Now, this doesn't mean two copies of Stand Together are an automatic choice for a Guardian's first 6 XP. There are plenty of other strong options. Beat Cop II is one of the best cards in the game. Keen Eye is underpriced and overpowered, like all the stat-boosting XP permanents. A super-weapon like Lightning Gun is not a bad idea, either. But Stand Together is definitely competitive with all of these, and a great thing to pick up before the campaign is done.