Sharkling

Does Vi's legend trigger on the chain without 3 excess damage assigned?

Vi, Destructive

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Sharkling

Does Vi's legend put a trigger on the chain even if 3 excess damage has not been assigned? For example, if I attack a 4-Might unit with Sharkling (Assault 4), can I sacrifice at some point? Does Vi's legend trigger on the chain without 3 excess damage assigned?