If this card had 3 icons and said "Commit only to a skill test you are performing during the Mythos phase," I would still consider taking this card in some Guardian decks.

This card can do that and it can played to boost some early action checks. I think it's quite good. Guardian characters normally want to go first anyways in order to clear out enemies, so they get good use out of it.

It's true that this card loses a little bit of utility if there are multiple people using it, but I think that it doesn't diminish it enough to say that only one investigator can use it exclusively.

I find this card is easier to consistently use more than Inquiring Mind, Last Chance, and Rise to the Occasion. One thing you can normally count on in Arkham Horror: There will be encounter cards, and they will try to kill you.

This is an incredible card. Lets break down why:

It has 3 wild icons. Extreeme value with complete flexibility, whether it's to kill an enemy, evade it or just grab a clue it's great card-to-bonus value.

But there is a downside, two actually, every action taken in a round kills one icon. Thus if you go second the card is effectively blank. This is actually the smaller downside, the other being "Commit only to a skill test you are performing". One of the strengths of skill cards is the fact that you can chuck em at a buddy, this is especially true for Unexpected Courage, a card that occupies the same deckslot this one does.

The first weakness, loosing icons, is largely mitigated by the fact that the card can be played at full value in response to events and cards drawn in the mythos phase. Rotting Remains for example, this in fact is the cards's greatest strength in my opinion.

So. 1 extra icon at the cost of only being playable selfishly. That's not a terrible trade.

This card is good. If you can fit an Overpower or Unexpected Courage then consider this one instead.

If two guardians show up to the party, one of them will probably have to change.

This card is an auto-include, probably over unexpected courage. If you play it for encounter card protection, you will be pretty resilient against treacheries.

Also, you are probably going first to nab bad guys or defeat enemies for allies.

AND even if you don't use it on a first action in a turn, you can use it on the second for an unexpected courage.

HOWEVER if you are in a two+ guardian party, someone probably will need to change this card out for something.

The possibilities of running this card next to Inquiring Mind, mean some investigators will have high quality skill cards.