Urza, Lord High Artificer, Worldwalker Helm, and Echo Storm

Prerequisites

• Urza, Lord High Artificer on the battlefield
• Worldwalker Helm on the battlefield
• Echo Storm in hand

Steps

1. Create a copy of Worldwalker Helm, which will also create a Map token
2. Activate Urza's first ability by tapping a Worldwaker Helm and a Map, adding
3. Activate a Worldwalker Helm by paying and tapping it, creating a token copy of the Worldwalker Helm token and a Map token for each Worldwalker Helm you control
4. Activate Urza's first ability twice by tapping two Maps, adding
5. Repeat from step 3

Results

• Infinite blue mana
• Infinite Map tokens
• Exile your library
• Cast all spells in your library
• Infinite copies of a specific artifact