Cast Faceless One by paying {0} due to Pearl-Ear.
When Faceless One enters the battlefield, Cloudstone Curio triggers, returning Ugin's Mastery from the battlefield to your hand.
Cast Ugin's Mastery by paying {0} due to Pearl-Ear.
When Ugin's Mastery enters the battlefield, Cloudstone Curio triggers, returning Faceless One from the battlefield to your hand.
Repeat.

Infinite ETB

Infinite LTB

Infinite storm count

Pearl-Ear, Imperial Advisor

Cloudstone Curio

Faceless One

Ugin's Mastery

Cast Faceless One by paying {0} due to Pearl-Ear.
When Faceless One enters the battlefield, Cloudstone Curio triggers, returning Case of the Shattered Pact from the battlefield to your hand.
Cast Case of the Shattered Pact by paying {0} due to Pearl-Ear.
When Case of the Shattered Pact enters the battlefield, it and Cloudstone Curio trigger.
Resolve the Case of the Shattered Pact trigger, causing you to search your library for a basic land card and put it into your hand.
Resolve the Cloudstone Curio trigger, returning Faceless One from the battlefield to your hand.
Repeat.

Put all basic lands from your library into your hand

Case of the Shattered Pact

Cast Ugin's Mastery by paying {0} due to Pearl-Ear.
When Ugin's Mastery enters the battlefield, Cloudstone Curio triggers, returning Case of the Shattered Pact from the battlefield to your hand.
Cast Case of the Shattered Pact by paying {0} due to Pearl-Ear.
When Case of the Shattered Pact enters the battlefield, it and Cloudstone Curio trigger.
Resolve the Case of the Shattered Pact trigger, causing you to search your library for a basic land card and put it into your hand.
Resolve the Cloudstone Curio trigger, returning Ugin's Mastery from the battlefield to your hand.
Repeat.

Combos with "Pearl-Ear, Imperial Advisor"