All permanents on the battlefield (Deadeye Navigator is paired with Urza).
({1} magic symbol) ({U} magic symbol) available.
Steps
Activate Urza by paying ({1} magic symbol) ({U} magic symbol) , blinking it.
When Urza enters the battlefield, it and Deadeye Navigator's soulbond ability trigger.
Resolve the Deadeye Navigator trigger, repairing it and Urza.
Resolve the Urza trigger, creating a 0/0 Construct artifact creature token.
Activate Urza's first ability by tapping the Construct, adding ({U} magic symbol) .
Activate Ashnod's Altar by sacrificing the Construct, adding ({C} magic symbol) ({C} magic symbol) .
Repeat.
Notes
Once you have infinite mana, you may forego sacrificing the Constructs. You may also use the mana to activate Urza's ability and/or blink any other creature(s).
Results
Infinite LTB.
Infinite ETB.
Infinite sacrifice triggers.
Infinite death triggers.
Infinite colorless mana.
Infinite creature tokens.
Infinite blue mana.
Infinite blinking.
Exile your library.
Cast all cards in your library without paying their mana costs.