Zethi, Arcane Blademaster | Nexus of Fate | Scroll of Fate

Cards

You have a way to kill a creature.
An opponent is unable to block and kill your creatures.
({5} magic symbol) ({U} magic symbol) ({U} magic symbol) available on each extra turn.

({1} magic symbol) ({WU} magic symbol) ({W} magic symbol) ({U} magic symbol) plus enough mana to pay for commander tax, if applicable, on the first turn available.

Activate
Scroll of Fate by tapping it, manifesting
Nexus of Fate.
Kill
Nexus of Fate, causing it to be put into your graveyard.
Cast
Zethi kicked once by paying ({1} magic symbol) ({WU} magic symbol) ({W} magic symbol) ({U} magic symbol) and commander tax, if applicable.
Zethi enters the battlefield, exiling
Nexus of Fate from your graveyard with a kick counter on it.
During any other turn, declare
Zethi as an attacker attacking an opponent unable to block and kill it.
Zethi triggers, causing you to pay ({5} magic symbol) ({U} magic symbol) ({U} magic symbol) to cast a copy of
Nexus of Fate.
Resolve the
Nexus of Fate copy, causing you to take an extra turn after this one and shuffle your library.
Repeat from step 5 each turn.