The team play feature is not just good for sharing the love of assets, but also allow others taking the play quota to skip Attack of Opportunity when playing those assets. Making this a great card for soak, Firearm, Spell users looking to refresh Asset even while in the mess of fighting. (The one who take play action to play Ever Vigilant (4) does have to deal with one AoO.)
If you are coming to rescue someone from enemies, you might not even have to engage it or risk friendly-fire. Instead just play this card. They might have just the asset that help dealing/evading that enemy on hand, only if they are Fast... well Ever Vigilant (4) is going to grant them that dream. It's like an uber-one-off-Fence comes flying to them : Works with all traits, no setup, and get both Fast and -1 discount! This allow team to recover from unlucky setup turns and make a come back even if enemies are already sticking in their threat area.
Since this card is looking to be the strongest at the start of scenario where you are all together, you may wish to communicate if you managed to mulligan into this card or not to influence mulligan decision of the other players in your party. (Or use Stick to the Plan)
Mulligan occurs in player order, the with this card as the lead may allow more efficient setup. Especially that it is "4 assets in total" as a group, you need to talk about how you share this quota. Below are relevant rules for reference.
Appendix III: Setting Up The Game
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- Choose one of those investigators to be the lead investigator for this game.
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- Draw opening hands. Each player draws 5 cards. Each player, in player order, may mulligan once at this time.
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If the players are instructed to perform a sequence "in player order," the lead investigator performs his or her part of the sequence first, followed by the other players in clockwise order. The phrase "the next player" is used in this context to refer to the next player (clockwise) to act in player order.