Aether Burst is the ability to use one´s energy from one´s Aether and make a sphere of energy. Being a high-powered concentrated energy it packs a lot of punch, but it´s also very risky.
In case you would fail to use that power due to not being able to control the energy correctly the result is the same as causing yourself to self-explode. This causes a lot damage to it´s user and is therefore not highly recommended.
However if you succeed using an Aether Burst you can also use it to blast away surrounding enemies. In order to use this power to one´s own advantage, being either smart and/or creative increases one´s possibilities for variation leading to higher success-rate in battle.
Aether Burst is the 2nd and final phase to utilizing this ability. In order use it, one must first make use of Phase One - Aether Leakage - and then causing an explosion.