NOTE: This combo fails if you target an opponent that does not have an instant or sorcery card in their library that can target a creature.
({2} magic symbol) available.
Steps
During the end step prior to your turn, activate Grinning Totem by paying ({2} magic symbol) and tapping it, causing you to search an opponent's library for an instant or sorcery card that can target a creature and exile it with the ability to cast it until your next upkeep.
At the beginning of your upkeep, Grinning Totem triggers, attempting to put the instant or sorcery into its owners graveyard, but instead exiling it with a void counter due to Dauthi Voidwalker.
Activate Dauthi Voidwalker by tapping and sacrificing it, causing you to cast the instant or sorcery without paying its mana cost, targeting Tethmos High Priest.
Tethmos High Priest triggers, returning Dauthi Voidwalker from your graveyard to the battlefield.
Holding priority, activate Lightning Greaves' equip ability by paying ({0} magic symbol) , attaching it to Tethmos High Priest.
Resolve the instant or sorcery spell, causing it to do nothing as Tethmos High Priest is now an illegal target, and then exile it with a void counter on it due to Dauthi Voidwalker.
Activate Lightning Greaves' equip ability by paying ({0} magic symbol) , attaching it to Dauthi Voidwalker.