Sometimes it's better to not use ally (in the next turn prepare for blocking) or even hero. From solo perspective if you can remove scheme by one card, this is very good. What's more 6 threat on one scheme is very rarely (but for example Under Pressure in campaign got 6 threat). In term of effiency this is 1 card per 2 thwart (+ exhaust). In justice this is not as much exciting, but in multi-aspect build this can really help.
New expanions on horizon (Agents of Shield) probably will raise potential of this card even more.
Solo this card is (A-C) B+ In multiplayer B-