Cast Wall of Stolen Identity by paying {3}{U}.
Wall of Stolen Identity enters as a copy of Sharuum.
Put Sharuum into the graveyard due to the legend rule.
Wall of Stolen Identity triggers, returning Sharuum from your graveyard to the battlefield.
Put Sharuum into the graveyard due to the legend rule.
Sharuum enters the battlefield triggers, returning itself from your graveyard to the battlefield.
Repeat from step 5.

Infinite ETB

Infinite LTB

Sharuum the Hegemon

Wall of Stolen Identity

Activate Adarkar Valkyrie by tapping it, targeting any legendary creature you control.
Cast Wall of Stolen Identity by paying {3}{U}, choosing to have it enter the battlefield as a copy of the legendary creature targeted in step 1.
Put the legendary creature into your graveyard due to the legend rule.
Adarkar Valkyrie and Intruder Alarm trigger.
Resolve the Intruder Alarm trigger, untapping all creatures.
Holding priority, activate Adarkar Valkyrie by tapping it, targeting Wall of Stolen Identity.
Resolve the Adarkar Valkyrie trigger from step 4, returning the legendary creature to the battlefield from your graveyard.
Put Wall of Stolen Identity into your graveyard due to the legend rule.
Adarkar Valkyrie and Intruder Alarm trigger.
Resolve the Intruder Alarm trigger, untapping all creatures.
Holding priority, activate Adarkar Valkyrie by tapping it, targeting the legendary creature.
Resolve the Adarkar Valkyrie trigger from step 9, returning Wall of Stolen Identity to the battlefield from your graveyard as a copy of the legendary creature.
Repeat from step 3.

Combos with "Wall of Stolen Identity"