Sidisi, Undead Vizier, Helm of the Host, and Beacon of Tomorrows

Prerequisites

• Sidisi, Undead Vizier on the battlefield
• Helm of the Host on the battlefield
• Beacon of Tomorrows in the library
• Helm of the Host attached to Sidisi
• each turn available

Steps

1. At the beginning of combat on your turn, Helm of the Host triggers, creating a non-legendary copy of Sidisi with haste
2. The non-legendary Sidisi enters the battlefield, triggering its exploit ability, sacrificing itself
3. Sidisi's second ability triggers, causing you to search your library for Beacon of Tomorrows, put it into your hand, and shuffle your library
4. Cast Beacon of Tomorrows by paying , causing you to take an extra turn after this one and shuffle it into your library
5. Repeat

Results

• Infinite turns