Cast Echo of Eons by paying ({4} magic symbol) ({U} magic symbol) ({U} magic symbol) , causing each player to shuffle their hand and graveyard into their library, and draw seven cards.
Nekusar triggers for each card your opponent draw this way, giving each opponent seven poison counters.
Cast Echo of Eons from your graveyard for its flashback cost by paying ({2} magic symbol) ({U} magic symbol) , causing each player to shuffle their hand and graveyard into their library, and draw seven cards, and exiling Echo of Eons.
Nekusar triggers for each card your opponent draw this way, giving each opponent seven poison counters.
Each opponent loses the game due to having ten or more poison counters.