Martian Manhunter can be unlocked through his challenge. Afterwards, he can be obtained randomly from the Challenge Booster Pack, Most Wanted Pack, and the newly-added Apokolips Darkseid Challenge Pack or as 1 of the 3 guaranteed cards in the Alien Invasion Pack. Obtaining him from these packs will NOT unlock him for direct promotions.
Strategy
Martian Manhunter is a well-rounded character with good specials, strong combos, stunning and long range hits, and great versatility. His passive motivates players to use light basic attacks, causing either stun, power drain, or mental damage over time. From a different angle, Martian Manhunter can be considered a decent utility character.
In a sample of 282 light basic combos, there are 75 (26.6%) stuns, 80 (28.3%) power drains, 76 (27.0%) mental damages and 51 (18.1%) did not offer a combo ender.
It appears that the mental damage effect deals 4% of his damage stat, spread over 3 hits, while his stun deals 2%, both of which are not affected by basic damage modifiers but are increased by global damage modifiers (e.g. Harley Quinn's S2). The power drain hit is a flat 50 damage that is unaffected by anything other than bleed's +20% damage. In Dead Zone, his combo ender remains a 2% damage hit instead of the standard 3%. His stun effect from the combo ender can be blocked.
Ra's Al Ghul's Dagger can be used on him to get a power drain effect more regularly. However, note that its power drain will only apply on his power drain or stun hits, and will not activate on a mental damage effect. While Gauntlets of Azrael's max health increase scales well with his high base health, his low-damage combo enders use its lifedrain rather poorly.
Martian Hunter Garb is almost mandatory on him, giving him increased maximum health and heal on s2 that works well with his high base health, and unblockable chance on basic attacks. Blocking gear such as the Charged Disc is also suggested to take full advantage of Martian Manhunter's health.
Using light basic attacks on a stunned opponent will not yield the combo ender. If you stunned your opponent and do not have a special to follow up, you can immediately use a single light basic attack, stop briefly, and then use another light basic attack combo, which has the usual chance of offering the combo ender while your opponent is unable to block, although this is quite tricky to pull off.
Interactions
Please note that battles are highly situational: this section only mentions cards that have mechanics that, for any reason, are particularly effective with/against, or particularly ineffective against Martian Manhunter. Having a card that "counters" Martian Manhunter does not mean it is always a good choice.
Good With
Batman/Prime: Batman Prime can aid Martian Manhunter/Prime by giving him 25% bonus damage
Harley Quinn/Animated: Animated Harley Quinn can give Martian Manhunter/Prime a 20 percent bonus of not only damage, but also power generation.
Ra's al Ghul Scimitar(gear card):It causes every hit in a combo ender to apply power drain, instead of applying it just once. But this gear is good for Martian Manhunter/Prime because Martian Manhunter himself will have a chance to power drain, which will drain even more power.
Catwoman/Batman Returns: With one of Martian Manhuner/Prime's telepactic attacks being the minor damage-over-time, Catwomen can give it a 100% boost.
Abilities
Telepathic Attack: Martian Manhunter's Basic combo has a chance of launching a Telepathic Attack, which causes random effects on his opponent.
Gold
750/1200
Promotion Cost 211,000
Challenge Mode, Challenge Booster Pack, Alien Invasion Pack, Special Challenge Booster Packs