The Thunder Maxim

Thunder was a violent element by nature. Although both Thunder-type spells and Fire-type spells were Offensive spells, there was a vast difference between the two.

Fire-type Offensive spells were mostly longer-lasting or used high temperatures to burn their opponents. These spells could be sustained for extended periods but their explosive powers were weaker by comparison. 

On the other hand, Thunder-type spells were distinctive in their instantaneous explosive powers. Their biggest advantage was that they were extremely violent, and could detonate an explosion of unparalleled power in an instant.

The same was true of the Thunder Maxim. A violent, destructive aura filled the surrounding atmosphere. Despite Merlin's wide repertoire of tactics, if even the slightest trace of the power of the Thunder Maxim had leaked out, he would not be able to withstand the terrifying power of the Thunder Maxim.