Beledros Witherbloom | Urza's Saga | Agatha's Soul Cauldron

(and two other cards)

Beledros Witherbloom and
Gristleback in exile (exiled by
Agatha's Soul Cauldron).
All other permanents on the battlefield.
Urza's Saga has two lore counters on it.
Lands you control except
Urza's Saga can tap to produce at least ({2} magic symbol) .
Your life total is at least 11.
The number of artifacts you control plus
Arwen's toughness is equal to or greater than 9.

Activate any number of lands except
Urza's Saga by tapping them, adding at least ({2} magic symbol) .
Activate
Urza's Saga's second ability by paying ({2} magic symbol) and tapping it, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control, and that enters the battlefield with a number of +1/+1 counters equal to
Arwen's toughness.
Activate the Construct using
Beledros Witherbloom's ability by paying 10 life, untapping all lands you control.
Activate the Construct using
Gristleback's ability by sacrificing it, causing you to gain at least 10 life.
Repeat.
If the number of artifacts you control plus
Arwen's toughness is equal to or greater than 10, this combo nets infinite life, and if other lands you control can tap to produce at least ({3} magic symbol) , this combo nets infinite mana.
If you get infinite life and infinite mana, you may forego sacrificing the Constructs.