Legendary Land Boseiju, Who Shelters All enters the battlefield tapped.
Rare
{T}, Pay 2 life: Add {1} to your mana pool. If that mana is spent on an instant or sorcery spell, that spell can't be countered by spells or abilities.
Illus. Ralph Horsley

12/1/2004: 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."
12/1/2004: 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.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern