Raven/Prime

Information on her passive is currently outdated.

Raven Prime can be unlocked through Challenge Mode. Otherwise, she can be obtained in either the Challenge Booster Pack or Most Wanted Pack, but this will not unlock her for direct promotions. If you want to obtain Raven (especially since she is incredibly strong even without promotions due to her passive), the Most Wanted Pack may be a better choice due to its limited pool.

She is often considered one of the most influential characters to ever hit Injustice Mobile, rivaling and possibly even surpassing the likes of Killer Frost or Deathstroke/Arkham Origins, bringing a new era to the game with her counterintuitive passive that has an impact that simply cannot be overstated.

Strategy
When Raven falls below 20% health, she swaps health with her current opponent. This means after the switch she will have her opponent's percentage health, and they would have her percentage health. When executed well, this essentially means she has a free ~80% maximum health damage on two opponents, while healing herself by ~160% of her maximum health. Even better is that this does not count as healing - it cannot be reduced by Killer Frost/Regime's passive, making Raven the best possible counter against her. This also does not require any power, making her very powerful against Killer Frost/Prime. Finally, since while Deathstroke/Arkham Origins's Point Blank can do potentially insane amounts of damage (over 70,000), it spreads its damage over 4 hits; with each hit below 20,000, it is relatively easy for it to trigger Raven's passive, making her strong against the three possibly most dangerous cards in multiplayer.

The health swap threshold may be lower than you expect, since most fall below % health passives are at 40%. For visual reference, it will be triggered when she falls lower than 3 small bars on her health bar (count by the top edge of the bar).

Raven is known for bringing about the rise in popularity of 1-hit special 2s, while special 2s with many hits are the norm for newer cards. In fact, the last challenge character released with a 1-hit special 2 (not counting the rework of Harley Quinn/Arkham) is Zod/Prime, way back to the very beginnings of challenge mode itself. However, Ares/Prime, released shortly after Raven, is infamous for having an immensely powerful one-hit special 2.

Raven is also extremely popular for the Nightmare stage of Challenge Mode, particularly challenge boss fights due to her passive, which is even more effective against challenge bosses with their unusually high health for their level.

Previously, Area Effect will trigger Raven's passive when she is tagged out, but it will only replace the aggressor's health with Raven's without changing Raven's own health. It was later fixed and now Area Effect will not trigger Demonic Rage.

Reflect damage and Radiation will trigger Demonic Rage. Demonic Rage will be triggered even if Raven is invulnerable as long as she is under 20% (through Area Effect damage). The Ibistick's burn will trigger Demonic Rage - and Harley Quinn's s2 will apply the burn, no matter which option is chosen.

Occasionally, if a character is tagged out immediately after using a super that triggered Demonic Rage, Raven will health swap with the next character who tags in instead.

Gear
Raven has flexible gear options. She can be overwhelmingly powerful either as main fighter or support.

As a main fighter (i.e. with high level and promotions), she can deal decent damage through her basic attack and specials. She can use basic damage boosts well as her full light combo does 13% damage, compared to the 9% norm. Ra's Al Ghul's Scimitar and Gauntlets of Azrael are both excellent choices for this path.

In terms of specials, her personal gear, Demonic Cloak, has excellent synergy with her s2, giving her crit and lifedrain on special 2 as well as a power generation boost. A special damage gear such as Diamond Tipped Claws can be used, but is pretty optional.

A good overall setup would be Ra's Al Ghul's Scimitar, along with her Demonic Cloak, topped off with The Ibistick for its very strong power generation and special damage boost. While her good combo enders synergize with Gauntlets, Raven does not really need its constant heals as much as most characters. However, Gauntlets' high maximum health boost can be useful against strong unblockable specials in high level play, such as when facing Harley Quinn/Arkham, Bane/Luchador, or Killer Frost/Prime.

Finally, she can also be used as a devastating support character. While she does not bring anything to the team if she is knocked out (unlike, say, Harley Quinn or Lex Luthor), her insane damage potential is just as strong, if not stronger, if she has low stats. Block gear is incredibly useful for getting her passive triggered when she is a support character.

Fourth World Set is a good choice on her, as the set effect with 3 pieces equipped will restore a small amount of health upon knock out, triggering her passive at the same time, making it unavoidable for her to swap health at least once. She could also make use of the variety of stats it brings. When fighting against Raven in Online Battles, it is a very good idea to check whether she has the full set equipped since it would require drastically different strategy. If you are experiencing crashes from viewing enemy team gear, you could find out whether she has the set during the match (the set doesn't have basic damage/crit and single heal on specials, for instance). If she does have the full set, try to knock her out with a strong multi-hit special by a character who already has low health, and preferably only after her teammates have been knocked out.

Interactions
However, Raven is somewhat leaning towards the more black-and-white side of things: her passive makes her rather binary, so countering becomes more significant.

Good with:

 * Wonder Woman/600: Her passive gives Raven 30% more damage and power generation.
 * Killer Frost/Regime: Like Batgirl/Cassandra Cain, Raven's damage potential is highest when her opponent has high current health, and Regime Killer Frost severely punishes characters at lower health as it is almost impossible to heal back, making them a very unforgiving combination.
 * Killer Frost/Prime: It is very hard to get rid of Raven without using at least a 1-hit s2. Killer Frost's passive halves enemy power generation, making it take twice as long to reach the required power level; basic/crit gear become less than useless as you can't gain power from basic attacking Raven when you are about to trigger her passive.

Good against:

 * Killer Frost and Deathstroke/Arkham Origins: As explained above.
 * Black Adam/Regime: He cannot choose to not damage Raven with his passive - which deals a large amount of damage that cannot deal a knock out blow - making it easy to accidentally trigger her passive.
 * Green Lantern/Red Lantern Hal Jordan: His passive lets him have a quick and early access to reduced opponents health to cinder, and couple with his high health, this can easily lets Raven swaps health with him if her health reaches below the limit.

Countered by:

 * Batman, primarily Batman/Arkham Origins, Batman/Arkham Knight and Batman/Beyond Animated: Militarized Batmobile greatly empowers their Super Move, which is already one of the simplest way to deal with Raven, especially since Arkham Origins Batman already starts with two bars (and Arkham Knight Batman can opt for the same), and Animated Batman Beyond's passive causes his super to grant him a temporary crit boost. However, note that the invulnerability will not prevent Raven from swapping health if the Super Move itself did not knock her out, although if you manage to somehow screw up, it will give you precious moments to react and tag out Batman. Also, the strong Area Effect on the Militarized Batmobile means even if you are unable to hit Raven directly with the super, you can safely bring her to very low health with the area effect, allowing you to easily knock her out from there.
 * Additionally, Arkham Origins Batman is also a strong counter against both versions of Killer Frost, Raven's common partners in crime.
 * Ares: His s2, God Smack, deals incredible amounts of 1 hit unblockable damage, making it extremely easy for him to knock out Raven.
 * Harley Quinn, particularly Harley Quinn/Animated: Animated Harley works well against Raven in many ways. Her passive allows her or her teammates to reach s2/super faster and cause them to hit harder. All three options of her s2 are valid options: the massive heal allows her team to recover from a sudden drop in health; the unblockable bomb can deal ~40k 1-hit damage and knock out Raven quickly, and the damage boost will make it even easier to achieve one high hit. However, be careful about using the bomb against Raven. Because of a complication in how specials interact, it is possible (albeit rare) for Raven to start using a special before the bomb finishes, which allows Raven to take the bomb damage but prevents her from being knocked out (i.e. she will stay at 1 health if she was already fairly low). This will trigger Raven's passive, in turn bringing Harley to 1 health to be immediately knocked out by Raven's special. Therefore, it's advised to only rely on the bomb if Raven has less than 1 bar of power or if you completely lack practical s2 or supers.
 * Doomsday/Containment: He can afford to be at low health more so than almost any other card. Additionally, his multi-hit s2 also makes him even more suited to deal with Fourth World Raven.

Abilities
Here are Raven's abilities.

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

Trivia

 * Prior to her challenge release, it is possible to encounter a silver Prime Raven as one of the random opponents in Bonus Battle 6, with a different but unknown passive.
 * Upon release, Demonic Rage glitches if you tag out right as it is triggered, causing your opponent to freeze in place and take any hit you throw without retaliation, while an image of Raven appears behind your active character.
 * Previously, her passive has a catch: the resulting health after the trigger depended on % health, but whether it triggers depended on absolute health. It means it was possible for Raven's passive to trigger and lose health while her opponent gain health if she has lower maximum health. For example, if her opponent has 100k maximum health but 15k left, while Raven has 50k maximum health and falls to 9k (which is lower than 20% of her maximum), her passive will trigger because it thinks her opponent has higher health. However, after the switch she only gets 15% (15k/100k) of her own maximum health, which is 7.5k, lower than her previous health, and the reverse happens on her opponent. This has since been removed.