Resolve the final trigger, causing you to pay ({3} magic symbol) to create two creature tokens.
Repeat from step 3.
Notes
If you sacrifice a creature to start using
Ashnod's Altar, the starting cost is reduced to ({1} magic symbol) . You can instead use a permanent that can sacrifice itself (like a Treasure token) or another method to sacrifice a permanent (like Braids, Arisen Nightmare).