Infinite Reflection attached to Treva's Attendant.
({1} magic symbol) ({U} magic symbol) available.
Steps
Cast Sandbar Merfolk either from your hand or from your graveyard by paying ({U} magic symbol) , causing it to enter the battlefield as a copy of Treva's Attendant due to Infinite Reflection.
If you cast Sandbar Merfolk from your graveyard, Sandbar Merfolk is not exiled by Abandoned Sarcophagus due to Infinite Reflection removing Sandbar Merfolk's cycling ability.