Corridor Monitor + Mana Echoes + Prismite + Saheeli, the Sun's Brilliance

UR identity

Commander legal

The 4 combo pieces

What must be in place

Saheeli does not have summoning sickness.
{U}{R} available, plus an additional {U}{R} if you control less than three creatures that share a creature type with Corridor Monitor

How to execute it

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

What the combo produces