Can Jodah, Archmage Eternal and Morophon, the Boundless make a card cost 0?

Question

Jodah, Archmage Eternal's ability says that I may pay one of each color rather than pay a spell's original mana cost

Morophon, the Boundless lets me choose a creature type and spells of that chosen type cost one of each color less to cast.

Simply, if I choose Wizards with Morophon, and I choose to pay one of each color to cast a Wizard spell with Jodah, will that creature cost 0??

Answer 1

Yes, that's correct. If the spell has the creature type you chose for Morophon, you can cast it for {0}—it will be free.

To determine the total cost of a spell we follow rule 601.2f:

601.2f. The player determines the total cost of the spell. [...] The total cost is the mana cost or alternative cost (as determined in rule 601.2b), plus all additional costs and cost increases, and minus all cost reductions. [...] If the mana component of the total cost is reduced to nothing by cost reduction effects, it is considered to be {0}.

Jodah, Archmage Eternal provides an alternative cost for the spell of {W}{U}{B}{R}{G}.

Morophon, the Boundless provides a cost reduction of (again) {W}{U}{B}{R}{G}.

We choose to use Jodah's alternative cost, and we subtract Morophon's cost reduction from it. The total cost is reduced to nothing, making the spell cost {0}.

So you get a free spell! Congratulations!

Answer 2

The total cost to cast a spell
= mana cost or alternative cost
+ additional costs and cost increases
- cost reductions

For creature spells of the chosen type,

• Jodah, Archmage Eternal's ability provides an alternative cost of {W}{U}{B}{R}{G}.
• Morophon, the Boundless's ability provides a cost reduction of {W}{U}{B}{R}{G}.

So,

The total cost to cast the spell
= mana cost or alternative cost ({W}{U}{B}{R}{G})
+ additional costs (none) and cost increases (none)
- cost reductions ({W}{U}{B}{R}{G})
= Free