Activate Altar of Dementia by sacrificing Felidar Guardian, causing target player to mill cards equal to Felidar Guardian's power.
Activate Liliana's second loyalty ability by removing three loyalty counters from it, returning Felidar Guardian from your graveyard to the battlefield.
Felidar Guardian enters the battlefield, blinking Liliana.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite mill

Infinite sacrifice triggers

Infinite self-mill

Felidar Guardian

Liliana, Death's Majesty

Altar of Dementia

Sacrifice Felidar Guardian to Viscera Seer to scry 1.
Activate Liliana's -3 ability to return Felidar Guardian to the battlefield from your graveyard.
When Felidar Guardian enters the battlefield, exile Liliana and return it to the battlefield with 5 loyalty.
Repeat.

Infinite scry

Viscera Seer

Activate Ashnod's Altar by sacrificing Felidar Guardian, adding {C}{C}.
Activate Liliana's second loyalty ability by removing three loyalty counters from it, returning Felidar Guardian from your graveyard to the battlefield.
Felidar Guardian enters the battlefield, blinking Liliana.
Repeat.

Infinite colorless mana

Ashnod's Altar

Sacrifice Felidar Guardian to Goblin Bombardment to deal 1 damage.
Activate Liliana's -3 ability to return Felidar Guardian to the battlefield from your graveyard.
When Felidar Guardian enters the battlefield, exile Liliana and return it to the battlefield with 5 loyalty.
Repeat.

Infinite damage

Goblin Bombardment

Activate Phyrexian Altar by sacrificing Felidar Guardian, adding one mana of any color.
Activate Liliana's second loyalty ability by removing three loyalty counters from it, returning Felidar Guardian from your graveyard to the battlefield.
Felidar Guardian enters the battlefield, blinking Liliana.
Repeat.

Infinite colored mana

Phyrexian Altar

Sacrifice Felidar Guardian to Carrion Feeder to put a +1/+1 counter on Carrion Feeder.
Activate Liliana's -3 ability to return Felidar Guardian to the battlefield from your graveyard.
When Felidar Guardian enters the battlefield, exile Liliana and return it to the battlefield with 5 loyalty.
Repeat.

Combos with "Liliana, Death's Majesty"