Activate Viscera Seer by sacrificing Boonweaver Giant.
When Boonweaver Giant dies as a legendary creature due to On Serra's Wings, Ratadrabik of Urborg triggers, creating a token copy of Boonweaver Giant that is a 2/2 Zombie in addition to its other types.
When the Boonweaver Giant token enters the battlefield, it triggers, returning On Serra's Wings from your graveyard to the battlefield attached to the token.
Resolve the Viscera Seer ability, causing you to scry 1.
Repeat.
This clever loop relies on transforming a non-legendary giant into a legendary threat using On Serra's Wings, allowing Ratadrabik of Urborg to catch its demise and forge a fresh zombie copy. Whenever that new Boonweaver Giant token enters the battlefield, its own ability immediately fetches the Aura right back from the graveyard to make the token legendary all over again. Viscera Seer provides the free sacrifice outlet needed to start the cycle anew, letting you endlessly churn through your deck with infinite scrys, death triggers, and enters-the-battlefield effects.