
There are so many things great about this card. It filters monsters from the encounter deck and redirects them to your mob handler. It spawns aloof enemies engaged with you, severely nerfing their revelation effeft. It saves the Guardian from drawing a bad card during mythos.
And finally, the upgraded version gives you an off global emergency cache when you kill whatever got stuck with it. Or, if you can't find an enemy, it gives you a pass on the encounter deck.
Use it, abuse it, don't look back.
Edit: Some folks say that forcing you to draw aloof enemies is a bad thing, but I couldn't disagree more. Even though aloof enemies won't be damaging you, they will be hindering you in other ways, especially in the newer scenarios. Generating doom, making objectives harder, etc. Clearing them out is a nice benefit. Even the older cards (wizard of the order, acolyte), forcing them to spawn engaged with you dramatically reduces their game effect.
Mandatory monster handling card imo.