Activate Saheeli by paying and tapping it, creating a token copy of Hyrax Tower Scout with haste.
When the token Hyrax Tower Scout enters the battlefield, it and Mana Echoes trigger.
Resolve the Hyrax Tower Scout trigger, untapping Saheeli.
Holding priority, if you control less than four creatures that share a creature type with Hyrax Tower Scout, repeat steps 1 through 3 one additional time.
Resolve all Mana Echoes triggers, adding C for each creature you control that shares a creature type with Hyrax Tower Scout for each trigger resolved this way.
Activate Urn of Godfire twice by paying 4, adding .
Repeat.
This dazzling loop transforms Saheeli, the Sun's Brilliance into an engine of endless replication by targeting Hyrax Tower Scout, whose entrance untaps Saheeli to keep the cycle going. With Mana Echoes watching the battlefield, every incoming Scout token dramatically scales your colorless mana reserves as the shared creature types accumulate. Meanwhile, Urn of Godfire acts as a flexible financial bridge, letting you cash in its mana-producing ability to fund Saheeli's activation costs and keep the rapid-fire mechanical symphony looping forever.