Activate Siren of the Silent Song by tapping it, adding {U}.
Activate Freed from the Real by paying {U}, untapping Siren of the Silent Song.
Siren of the Silent Song triggers, causing each opponent to discard a card and mill a card.
Repeat.

Infinite mill

Siren of the Silent Song

Freed from the Real

Paradise Mantle

Activate Clock of Omens by tapping it and Siren of the Silent Song, targeting Siren of the Silent Song.
Ertha Jo triggers, copying Clock of Omens' ability, targeting Clock of Omens.
Resolve both Clock of Omens  abilities, untapping it and Siren of the Silent Song.
Siren of the Silent Song triggers, causing each opponent to discard and mill a card.
Repeat.

Combos with "Siren of the Silent Song"