Dark Matter is a skill found in The Legend of Dark Witch 2. It is the signature skill of Mari.
The Legend of Dark Witch 2
The skill differs when used by the player compared to when it is used in the boss fight with Mari.
Player
Pressing the attack button will launch a small black hole straight forward. This projectile cannot damage enemies until you press the attack button again, which will stop the black hole from moving and increase its size. While Dark Matter is active, any enemies coming in contact with Dark Matter will take damage over time. It's very comparable to the Black Hole Bomb from Mega Man 9, though without the ability to aim it or suck enemies in. Interestingly, another Dark Matter can be shot out even if one is still active.
Upgrade
Like the other Technical Skills in The Legend of Dark Witch 2, Dark Matter can be upgraded to make it stronger. Upgrading Dark Matter will make the black hole bigger when the fire button is pressed a second time. It also allows the player to break gray blocks that appear in certain levels.
Super Effectiveness
Urken is weak to Dark Matter in The Legend of Dark Witch 2.
Mari (Bossfight)
During Mari's bossfight in The Legend of Dark Witch 2, when she reaches around half health, she will temporarily summon a black hole in the middle of the field. The size of it is comparable to when it is upgraded in the shop, and it comes with the added effect of attempting to suck the player in.
Brave Dungeon
Dark Matter reappears in Brave Dungeon as Mari's Revenge Magic. When using it, Mari will summon Dark Matter in the middle of the field, dealing damage to all present enemies.