Gigatas

An incantation for manipulating maiga into an immensely powerful destructive force, its use is heavily restricted within the countries of the world. Even rogue shapers only use it in dire need, as the feedback of channeling that much maiga wreaks havoc on the shaper's body. Death is not uncommon for unprepared shapers attempting gigatas as they get rent apart by the backlash of a truly enormous amount of energy.
Those who survive amassing the energy required for gigatas are now in posession of one of the most powerful weapons on Tarsis. A shaper will inately feel when they have enough maiga for gigatas, though weaker shapers may not recognize this and push themselves too far or not amass enough maiga. Due to the unstable nature of having so much maiga in one place, it tends to be released as a large beam by the adept, a blast like a massive bomb by those not powerful or trained enough to properly channel gigatas.
The incantation for gigatas starts in the mind, willing the maiga in the local environment to form up somewhere close to the shaper. This is often within the hands, as the tactile element of physically wrangling the maiga helps some with the incantation. Once a suitable amount of maiga is balled up near the shaper, they direct where they wish to aim the devastation and cry out "Gigatas!".
It cannot be overstated how dangerous gigatas is. Even the shapers within the Altean Army and Angor's Diezens, powerful as they are, won't resort to this without dire need. Those who use it are often reviled for the damage caused. Entire settlements have been wiped off the map by the careless use of gigatas, leaving large desolate craters or scorched trenches in their wake. 
It has been theorized that ancients have a particularly strong grasp on how to use gigatas, both avoiding or simply tanking through the feedback and being able to control the exact scale of which gigatas is used. Attempting gigatas without a critical mass of maiga for anyone else results in a violent backblast as the maiga blows up in the shaper's face, often literally.