Activate Emiel the Blessed by paying 3, blinking any other nontoken creature you control.
When the creature enters the battlefield, Blessed Sanctuary triggers, creating two 2/2 Unicorn creature tokens.
Activate Ashnod's Altar twice by sacrificing the Unicorns, adding CCCC.
Repeat.
This looping engine is masterminded by Emiel the Blessed, whose activated ability continually banishes and blinks another creature to trigger an endless chain of entering-the-battlefield events. Every time a nontoken creature drops back onto the battlefield, Blessed Sanctuary steps in to generate a Unicorn, an output that Adrix and Nev, Twincasters aggressively doubles into a pair of shiny new tokens. You can then feed those doubled Unicorns straight into Ashnod's Altar to harvest more than enough colorless mana to fuel Emiel the Blessed all over again, leaving you with boundless resources and a swelling army.