Cast the legendary creature in your hand by paying {0} due to Bard Class.
If Bard Class is level 3, its third ability triggers, exiling the top two cards of your library with the ability to play them until end of turn.
When the legendary creature enters, Cloudstone Curio triggers, returning the other legendary creature from the battlefield to your hand.
Repeat.

Infinite LTB

Infinite ETB

Infinite storm count

Exile your library with the ability to play the exiled cards until end of turn

Legendary Creature Castable for RG

Bard Class

Cloudstone Curio

Activate Hajar by sacrificing it.
When Hajar dies, Yomiji triggers, returning Hajar from your graveyard to your hand.
Resolve the Hajar ability, causing legendary creatures you control to get +1/+0 and indestructible until end of turn.
Cast Hajar by paying {0}.
Repeat.

Infinite death triggers

Infinite sacrifice triggers

Infinitely powerful legendary creatures you control until end of turn

Hajar, Loyal Bodyguard

Yomiji, Who Bars the Way

Cast Ruby either from your hand or from the command zone by paying {0} due to Bard Class plus commander tax, if applicable.
Activate Ruby by tapping it, adding {G}.
Activate Kogla by paying {G}, returning Ruby from the battlefield to your hand.
Repeat.

Ruby, Daring Tracker

Kogla, the Titan Ape

Agatha of the Vile Cauldron

Activate Domri's first ability by putting a loyalty counter on it, adding {R/G}.
Cast Wrenn and Six by paying {0}.
Wrenn and Six enters the battlefield, triggering Cloudstone Curio, returning Domri from the battlefield to your hand.
Activate Wrenn and Six's second ability by removing a loyalty counter from it, dealing 1 damage to any target.
Cast Domri by paying {1}.
Domri enters the battlefield, triggering Cloudstone Curio, returning Wrenn and Six from the battlefield to your hand.
Repeat.

Infinite damage

Domri, Anarch of Bolas

Wrenn and Six

Activate Hajar by sacrificing it.
When Hajar dies, Enduring Renewal triggers, returning Hajar from your graveyard to your hand.
Resolve the Hajar ability, causing legendary creatures you control to get +1/+0 and indestructible until end of turn.
Cast Hajar by paying {0}.
Repeat.

Combos with "Bard Class"