Coalition Relic

{T}: Add one mana of any color.
{T}: Put a charge counter on Coalition Relic.
At the beginning of your first main phase, remove all charge counters from Coalition Relic. Add one mana of any color for each charge counter removed this way.

The List

Modern Horizons 3 Commander

{T}: Add one mana of any color.
{T}: Put a charge counter on Coalition Relic.
At the beginning of your precombat main phase, remove all charge counters from Coalition Relic. Add one mana of any color for each charge counter removed this way.

Dominaria United Commander

Time Spiral Remastered

If you remove multiple charge counters from Coalition Relic at once, you may add a different color of mana for each one.

Only the first main phase each turn is considered a precombat main phase, even if additional main phases or combat phases are created.