Boseiju, Who Shelters All

From the Vault: Realms (V12) #2 · Mythic · Legendary Land

Boseiju enters tapped.
{T}, Pay 2 life: Add {C}. If that mana is spent on an instant or sorcery spell, that spell can't be countered.

Illustrated by Ralph Horsley · Released August 31, 2012

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2004-12-01 · wotc — The spell can't be countered if the mana produced by Boseiju is spent to cover any cost of the spell, even an additional cost such as a splice cost. This is true even if you pay an additional cost while casting a spell "without paying its mana cost."
2004-12-01 · wotc — Suppose mana produced by Boseiju is spent on a spell and an effect creates a copy of that spell. The copy can be countered, even though the original can't.