Myr Superion is a 2 mana 5/6 that comes with the following casting restriction:
Spend only mana produced by creatures to cast Myr Superion.
Under most circumstances this wouldn't be ambiguous, but I'm not sure how it interacts with type-changing effects. Specifically, I want to know whether Myr Superion could be cast with mana produced in the following ways:
- Blinkmoth Nexus is tapped for mana, then animated using some other mana.
- Palladium Myr is tapped for mana, then stops being a creature e.g. due to Song of the Dryads.
- Deathrite Shaman is tapped to activate its first ability, which goes on the stack because it is not a mana ability, and then stops being a creature before that ability resolves.
I wasn't able to find any lands which could produce mana using an ability that is not a mana ability, but I suspect I will be able to deduce that hypothetical outcome based on the others listed.
In other words, when casting Myr Superion does a mana source need to be a creature when the ability was activated, when the ability resolved, or when the Superion is cast?