Yes, her def debuff. Actually light has to rely on soul's def debuff, so having Amon allow more flexibility in the choice of your soul and Ex skill. I had her in my team since Apocalypse event, and i only replaced her this week with Uranus.
Also the control she brings on boss is really good, even if she isnt buffed by eidolon or weapon's skill (stun extend + assist atk up on raging enemy).
Ofc a light SR will be better, but there is no reason to choose a R instead of her.
Source : Help > Union > When a Leader goes MIAWhen a Leader fails to log in for two weeks or more, the Subleader automatically becomes the Leader.
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