Return of Reckoning

need a clarification. if hit and adversary using that style and all damage is absorbed by a shield spell, then no silence effect is applied; is it so ?

Shields do not prevent additional effects from occurring, which is kind of stupid but what the hell.

is there any immunity timer for the silence effect ? if so, how long does it last ?

I believe immunity timers are based on the initial duration of the crowd control that was applied.
Generally it's between 20 and 30 seconds and the cc types are share a grouped immunity.

Stagger, knock down and silence share an immunity type called unstoppable

Knockback, pull and root share an immunity type called immovable

certain skills also provide immunity to silence such as resolute defence or focused mind.

Silence immunity is part of the general CC immunity "Unstoppable" and its duration varies depending on the effect that triggered it.

thank you for your replies