This enemy has a combination of rule that maybe problematic for an inexperienced player like I was.

• Massive :
  • A ready enemy with the massive keyword is considered to be engaged with each investigator at the same location as it.
  • An enemy with the massive keyword cannot be placed in an investigator's threat area.
• Hunter :
  • During the enemy phase (in framework step 3.2), each ready, unengaged enemy with the hunter keyword moves to a connecting location, along the shortest path towards the nearest investigator. Enemies at a location with one or more investigators do not move.
• Prey :
  • If an enemy that is moving towards the nearest investigator has a choice between multiple equidistant investigators, that enemy must select among those investigators the one who best meets its "prey" instructions.

So

• Prior to this point it looks like Hunter enemy stops moving because someone move it from the map to threat area, which is intuitive to understand. In this case Massive monster does not enter anyone's threat area, but still Hunter stops working due to Massive "considered" engaged.
• If the lowest tries to lure it away, but there is someone with higher nearer, Prey does not matter and it moves to the nearest investigator anyway. (With large map like The Midnight Mask a misunderstanding like this goes uncorrected, until this scenario.)

When i first saw this card, like many others, i thought that it was good but not as good as Hyperphysical Shotcaster which is a bit broken, but still strong. Now when i have seen it in action many times, i have to conclude that this card is just broken, and that FFG has again managed to push Seeker even more over the top. So this card has a wild symbol, is practiced, of course you are running Practice Makes Perfect because it is the strongest skill-based card in the game and just makes you double-up on Deduction and Perception, and now on important tests you do not even care about ? Wow! It takes Rogues 3xp to put Justify the Means in their decks, 6xp for 2 copies, and Mystics need 10xp for Seal of the Elder Sign which is basically this card + a bit of power depending on your . Survivors have some tricks like Eucatastrophe but these cards are kinda swingy when it comes to consistency and it takes some tricks to use their cards to their fullest potential, but Seekers do not have those obstacles and they just spam clues right off the start. Picking up your clue after this test if you draw an autofail is non-important, because you already have atleast 5 INT or even more, so it is just an action or sometimes you do not even pick it back up if it is not on a location with a victory. This card needs some serious tabboo right now and it needs to say that it can cancel anything except because this is just too strong for already the strongest class in the game, it is just absurd. Maybe players with a limited collection will not understand its power, but playing with a full collection, yeah, printing cards like this in literally every expansion just makes me wonder why the hell do Seekers get the most powerful stuff all the time? Are they not broken enough?

Relevant "prey" + "only" rule for reference :

If an enemy's prey instructions contain the word "only," that enemy only moves towards and engages that investigator (as if it were the only investigator in play), and ignores all other investigators while moving and engaging. Other investigators may use the engage action or card abilities to engage the enemy.

• Non-bearer cannot stand on its way to get the engagement. It is also costly to help because you need an engage action.
• If the bearer got eliminated/resigned from the campaign it simply stay still and everyone else can pass through.

This card is bad with Lola (its like they don't want her to be viable), but is extremely good with Charlie, especially late game. Charlie can very conceivably have a card from all classes up given his extremely diverse card pool (e.g., typical pick is guardian and survivor for his card class. In an enemy handling deck, you could then grab David Renaut, Delilah and a Med Student. You now have all five classes in play).

That translates into a +5 attack that does six damage, a serious boss killer card.

As others have said you're going to want to sit on this card a bit, especially Charlie, to get the full effect. But once you've got a rainbow assortment of allies on the table, fire at will and watch the cackling politican send his army of free lancers into the boss' maw.

In addition to @olahren review: William has a nice interaction with Mariner's Compass, Fingerprint Kit, Archaic Glyphs and other multi-clue cards. If you find yourself investigating a location with one clue, you can now grab that second one from somewhere else.