Saheeli, the Sun's Brilliance, Mana Echoes, Breaching Hippocamp, and Prismite

Prerequisites

• Saheeli, the Sun's Brilliance on the battlefield
• Mana Echoes on the battlefield
• Breaching Hippocamp on the battlefield
• Prismite on the battlefield
• Saheeli does not have summoning sickness
• available, plus an additional if you control less than three creatures that share a creature type with Breaching Hippocamp

Steps

1. Activate Saheeli by paying and tapping it, creating a token copy of Breaching Hippocamp with haste
2. When the token Breaching Hippocamp enters the battlefield, it and Mana Echoes trigger
3. Resolve the Breaching Hippocamp trigger, untapping Saheeli
4. Holding priority, if you control less than four creatures that share a creature type with Breaching Hippocamp, repeat steps 1 through 3 one additional time
5. Resolve all Mana Echoes triggers, adding for each creature you control that shares a creature type with Breaching Hippocamp for each trigger resolved this way
6. Activate Prismite twice by paying , adding
7. Repeat

Results

• Infinite ETB
• Infinite colored mana
• Infinite colorless mana
• Infinite creature tokens with haste