KanjiJLPT N2
Violent

violent, get excited, enraged, chafe, incite

Mnemonic

A storm turns the sky white as a ninja watches his compass spin wildly out of control. The energy building is so violent that the compass explodes in his hand—the ninja is hurled backward through the blinding white storm, battered by its relentless fury.
Additional thoughts
Picture the ninja gripping a compass that spins faster and faster in the white-out storm until the violent energy detonates it. Storm + white sky + spinning compass + ninja = extreme violent force.
Quick recall
A storm blankets the sky white while a ninja's compass spins until it explodes with violent force.

Details

The keyword for 激 is violent. This kanji conveys the sense of something intense, fierce, or extreme in force or emotion. It describes actions or states that are sudden, powerful, and overwhelming, such as raging waters, intense anger, or drastic changes. The character captures the idea of something being stirred up or agitated to an extreme degree.
On'yomi
げき
Kun'yomi
はげ.しい