Bag-o-Tricks

Bag-o-Tricks is the name of all versions of Harley Quinn's SP2. It is a very unique special due to not only the effects offered, but also the mechanics involved.

Function
Bag-o-Tricks has three effects available: A damage boost, an Unblockable bomb (the only source of actual damage in the special), and a team-wide heal regain. Each effect is represented by a visual cue: the damage boost is represented by a picture of The Joker, the bomb is shown as dynamite, and the heal is a rose. The damage boost boosts all forms of damage by 50% temporarily (hearts will swirl around the character when active). The bomb deals damage equivalent to ~ 100% of Harley's damage stat, which is around half of the damage typically dealt by a SP2, likely due to the other effects offered. Meanwhile the rose heals all of her teammates by 30%. The effects are extremely unique and mimicked by no other special. They also perform the same effects for almost all versions of Harley, which can make even bronze Harley Quinn/Prime an excellent support character for golds due to her %-based damage boost and heal.

Harley's signature gear, .357 Revolvers, has excellent synergy with Bag-o-Tricks, and therefore all Harley Quinn versions. It offers a large team heal on her SP2, which stacks additively with the heal from Bag-o-Tricks, allowing for as much as a 55% heal from her SP2 (to her entire team).

Suicide Squad
Harley Quinn/Suicide Squad has a further modified version of Bag-o-Tricks. Due to her passive, she has a fourth trick: the ability to give both of her teammates 1 bar of Power immediately. This is represented visually by 3 red diamonds, Harley's logo.

Additionally, when combined with Deadshot, her bomb is transformed into C4. This does the same damage as the normal bomb, but also deals 20% of the C4's damage to the rest of the opponent's team. When combined with The Joker/Suicide Squad or The Joker Unhinged/Suicide Squad, the damage boost is converted into a surprise attack. The typical Joker photo is changed to a photo of Suicide Squad's Joker. The Joker (either version) will be called in when Harley selects this option, and will shoot his pistol once at her enemy, dealing exactly 100% of HIS damage stat (the damage is not based in any way on Harley). The damage from this option does not count as Special Dmage (it's damage is displayed by a white text instead of yellow), and therefore negates Superman/Injustice 2's passive. If either Deadshot or Joker dies before Harley, their respective options will no longer be available.

Trivia

 * Bag-o-Tricks is the only special who could potentially never deal damage to the enemy (Aquaman/Prime's SP2 could still be considered to do damage).
 * It is also the only special who could ever directly affect a teammate without use of a passive or any Gear.
 * Bag-o-Tricks is based on Harley Quinn's Character Power (equivalent of a passive) from the console game, as both have the same name and offer the same effects.
 * Interestingly, the two are spelled slightly differently, as the console version is named "Bag O' Tricks".
 * The stated minimum and maximum damage for Bag-o-Tricks is always the same.
 * The picture is obviously a reference to Harley's love, The Joker, also evidenced by the fact that she kisses it. The rose is also likely a reference to Posion Ivy, a plant-themes villain who is always a very close friend to Harley (and also one of her support cards).