Ao, the Dawn Sky, Mortuary, and Sakashima's Student

Prerequisites

• Ao, the Dawn Sky on the battlefield
• Mortuary on the battlefield
• Sakashima's Student in hand
• available

Steps

1. Cast Sakashima's Student by paying its mana cost
2. Choose to have it enter the battlefield as a copy of Ao
3. Put Sakashima's Student into your graveyard due to the legend rule
4. When Sakashima's Student dies, it and Mortuary trigger
5. Resolve the Mortuary trigger, putting Sakashima's Student from your graveyard onto the top of your library
6. Resolve the Sakashima's Student trigger, causing you to look at the top seven cards of your library and put Sakashima's Student onto the battlefield as a copy of Ao
7. Repeat from step 2

Results

• Infinite LTB
• Infinite ETB
• Infinite death triggers