The Joker/The Killing Joke

Killing Joke Joker can be bought directly with alliance credits, or obtained randomly through Most Wanted Packs. If he is obtained from the latter and then sold, the sale gives 18 alliance credits.

Strategy
Killing Joke Joker has a "on knock-out" passive like The Joker/Prime and The Joker/Insurgency, but is widely considered more powerful. While his health is extremely low, it is less of a concern as he gives his two teammates full power upon being knocked out.

His decent damage is further empowered by Harley Quinn/Animated's doubled 40% damage and power generation boost for Joker characters, as well as the fact that his heavy basic attack combo does 4 hits (essentially increasing his base damage for basic attacks to 1266).

Killing Joke Joker is very often built as a support character (non-promoted along with 2 promoted teammates) - very possibly the most popular (by % of usage) than any other character, as he is very effective at low stats and takes an extremely long time to promote through daily bonuses (and alliance support cards are globally useful so they are bought often instead). He is similar to, but likely even more so than, Raven/Prime in this regard.

Prior to the release of The Joker/Arkham Origins, for a long time, Killing Joke Joker was the strongest Joker.

Good with:

 * Shazam/Prime: he will be able to use his Supermove quicker upon Joker's KO'd.

Abilities
Here are Joker's abilities.

Support Cards and Gear
Here are Joker's support cards and gear.