The 5th basic attack can be charged twice, with the second stage offering the highest stun/anomaly damage.
Holding the button allows him to charge the first three basic attacks consecutively, speeding up his rotation.
What other characters do you have to build a around him? Lycaon [2.6 Rework] Simplified Guide | ZZZ Made EZ
Boosts charged basic attacks by 80%, making charge management essential.