Black Crystal

Black Crystals are a smaller and weaker variation of the Black Obelisks. They are also utilised more often. They are unique to Advance Wars: Dual Strike.

In-depth
Crystals are completely impassable and give no terrain stars. They cover one square and become plains tiles after destruction, although there is clearly rubble left over. Black Hole units within two spaces of the Crystal get 2HP restored, along with their fuel and ammo, for free. Along with the Black Obelisks, they are the only way to repair an Oozium.

They act as the main source of Black Hole's power in Dual Strike and were invented by Lash for the Bolt Guard's campaign in Omega Land. They produced massive amounts of energy and materials, but turned the surrounding area into desert and wasteland.

Appearances as a mission objective
The first time a Crystal appears is in the two-front mission Victory or Death!, where Koal uses one to bolster his forces. It is protected by Lash's Black Arc, which drops bombs to impede the progress of the Allied Nations.

Seven Crystals later appear in Healing Touch, where Kindle and Jugger oversee the restoration of a group of damaged Black Hole units in an area called "The Tower of Rebirth".

Finally, three Black Crystals appear in Means to an End. They act as the power for a barrier protecting the weak spots of Von Bolt's gargantuan Oozium, the Grand Bolt, and are protected by Kindle's forces.

Other appearances
Three Crystals supplement the Black Obelisk and a group of Minicannons in For the Future!. They also appear in a handful of Survival maps.