Activate Lazav by paying {5}, causing it to become a copy of Mirror-Mad Phantasm until end of turn.
Activate Lazav using Mirror-Mad Phantasm's ability by paying {1}{U}, shuffling Lazav into your library and milling your library due to not having a card named Mirror-Mad Phantasm in it.

Infinite self-mill

Lazav, the Multifarious

Mirror-Mad Phantasm

Activate Lazav by paying {2}, choosing to have it become a copy of Lesser Masticore if it doesn't have a -1/-1 counter on it, or Butcher Ghoul otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Lesser Masticore, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Infinite surveil

Lesser Masticore

Ashnod's Altar

Butcher Ghoul

Activate Lazav by paying {2}, choosing to have it become a copy of Lesser Masticore if it doesn't have a -1/-1 counter on it, or Nardole otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Lesser Masticore, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Nardole, Resourceful Cyborg

Activate Lazav by paying {2}, choosing to have it become a copy of Putrid Goblin if it doesn't have a -1/-1 counter on it, or Butcher Ghoul otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Putrid Goblin, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Putrid Goblin

Activate Lazav by paying {2}, choosing to have it become a copy of Putrid Goblin if it doesn't have a -1/-1 counter on it, or Nardole otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Putrid Goblin, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Activate Lazav by paying {2}, choosing to have it become a copy of Lesser Masticore if it doesn't have a -1/-1 counter on it, or Young Wolf otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Lesser Masticore, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Young Wolf

Activate Lazav by paying {2}, choosing to have it become a copy of Lesser Masticore if it doesn't have a -1/-1 counter on it, or Strangleroot Geist otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Lesser Masticore, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Strangleroot Geist

Activate Lazav by paying {2}, choosing to have it become a copy of Putrid Goblin if it doesn't have a -1/-1 counter on it, or Young Wolf otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Putrid Goblin, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Activate Lazav by paying {2}, choosing to have it become a copy of Putrid Goblin if it doesn't have a -1/-1 counter on it, or Strangleroot Geist otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Putrid Goblin, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Activate Lazav by paying {2}, choosing to have it become a copy of Safehold Elite if it doesn't have a -1/-1 counter on it, or Young Wolf otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Safehold Elite, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Safehold Elite

Activate Lazav by paying {2}, choosing to have it become a copy of Safehold Elite if it doesn't have a -1/-1 counter on it, or Strangleroot Geist otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Safehold Elite, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Activate Lazav by paying {2}, choosing to have it become a copy of Safehold Elite if it doesn't have a -1/-1 counter on it, or Nardole otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Safehold Elite, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Activate Lazav by paying {2}, choosing to have it become a copy of Safehold Elite if it doesn't have a -1/-1 counter on it, or Butcher Ghoul otherwise.
Activate Ashnod's Altar by sacrificing Lazav, adding {C}{C}.
When Lazav dies, if it was a copy of Safehold Elite, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Otherwise, Lazav's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Lazav enters the battlefield, it triggers, causing you to surveil 1.
Repeat.

Combos with "Lazav, the Multifarious"