Cast the non-card copy of Sign in Blood from exile by paying {B}{B}, unpreparing Scheming Silvertongue.
When you cast it, Spellweaver Helix's last ability triggers, allowing you to cast a copy of the Extra Turn Sorcery without paying its mana cost and take an extra turn after this one.
Resolve the copy of Sign in Blood, causing any player to draw two cards and lose 2 life.
Use the Repeatable Silvertongue Preparer to gain at least 2 life.
At the beginning of your second main phase, Scheming Silvertongue triggers, becoming prepared.
Repeat each turn.

Infinite turns

Lock

Extra Turn Sorcery

Repeatable Silvertongue Preparer

Spellweaver Helix

Scheming Silvertongue // Sign in Blood

Sign in Blood

Cast the non-card copy of Sign in Blood from exile by paying {B}{B}, unpreparing Scheming Silvertongue.
When you cast it, Spellweaver Helix's last ability triggers, allowing you to cast a copy of the Extra Turn Sorcery without paying its mana cost and take an extra turn after this one.
Resolve the copy of Sign in Blood, causing an opponent to draw two cards and lose two life.
When your opponent loses life, Bloodthirsty Conqueror triggers, causing you to gain 2 life.
At the beginning of your second main phase, Scheming Silvertongue triggers, becoming prepared.
Repeat each turn.

Combos with "Sign in Blood"