Cast Echo of Eons by paying {4}{U}{U}, causing each player to discard their hands and draw seven cards.
Nekusar triggers for each card your opponents draw.
Resolve the first trigger, causing the opponent to get a poison counter.
If the opponent has ten or more poison counters, they lose the game as a state-based action.
Repeat from step 3 for each remaining trigger.
If needed, cast Echo of Eons from your graveyard for its flashback cost by paying {2}{U}, causing each player to discard their hands and draw seven cards.
Repeat from step 2.

Each opponent loses the game

Nekusar, the Mindrazer

Echo of Eons

Phyresis

Cast Echo of Eons by paying {4}{U}{U}, causing each player to shuffle their hand and graveyard into their library and draw seven cards.
Fate Unraveler 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}{U}, causing each player to shuffle their hand and graveyard into their library, draw seven cards, and exile Echo of Eons.
Fate Unraveler 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.

Fate Unraveler

Cast Echo of Eons by paying {4}{U}{U}, causing each player to shuffle their hand and graveyard into their library and draw seven cards.
Kederekt Parasite 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}{U}, causing each player to shuffle their hand and graveyard into their library, draw seven cards, and exile Echo of Eons.
Kederekt Parasite 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.

Kederekt Parasite

Cast Echo of Eons by paying {4}{U}{U}, causing each player to discard their hands and draw seven cards.
Razorkin Needlehead triggers for each card your opponents draw.
Resolve the first trigger, causing the opponent to get a poison counter.
If the opponent has ten or more poison counters, they lose the game as a state-based action.
Repeat from step 3 for each remaining trigger.
If needed, cast Echo of Eons from your graveyard for its flashback cost by paying {2}{U}, causing each player to discard their hands and draw seven cards.
Repeat from step 2.

Razorkin Needlehead

Cast Tainted Strike by paying {B}, giving Fate Unraveler +1/+0 and infect until end of turn.
Cast Echo of Eons by paying {4}{U}{U}, causing each player to shuffle their hand and graveyard into their library and draw seven cards.
Fate Unraveler 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}{U}, causing each player to shuffle their hand and graveyard into their library, draw seven cards, and exile Echo of Eons.
Fate Unraveler 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.

Tainted Strike

Cast Tainted Strike by paying {B}, giving Kederekt Parasite +1/+0 and infect until end of turn.
Cast Echo of Eons by paying {4}{U}{U}, causing each player to shuffle their hand and graveyard into their library and draw seven cards.
Kederekt Parasite 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}{U}, causing each player to shuffle their hand and graveyard into their library, draw seven cards, and exile Echo of Eons.
Kederekt Parasite 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.

Combos with "Echo of Eons"