Activate Phyrexian Devourer by exiling the top card of your library.
Repeat step 1 until you have an empty library.
Resolve the first Phyrexian Devourer ability, putting a number of +1/+1 counters on it.
If Phyrexian Devourer's power is at least seven, it triggers, causing you to sacrifice it.
Repeat from step 3 for each remaining trigger.
Cast Walk the Aeons by paying ({4} magic symbol) ({U} magic symbol) ({U} magic symbol) , causing you to take an extra turn after this one, and put Walk the Aeons on the bottom of your library due to Wheel of Sun and Moon.
Move to your next turn, drawing Walk the Aeons from your library.