Cavern of Souls
Land
As this land enters, choose a creature type.
: Add 
.
: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.
Pedro Correa
The Lost Caverns of Ixalan (LCI)
• #410eRulings
The spell can't be countered if the mana produced by Cavern of Souls is spent to cover any cost of the spell, even an additional cost such as a kicker cost. This is true even if you use the mana to pay an additional cost while casting a spell "without paying its mana cost."
(wotc • 2023-11-10)
You must choose an existing creature type, such as Human or Warrior. Card types such as artifact can't be chosen.
(wotc • 2023-11-10)
You must choose an existing creature type, such as Human or Warrior. Card types such as artifact can't be chosen.
(wotc • 2018-12-07)
The spell can't be countered if the mana produced by Cavern of Souls is spent to cover any cost of the spell, even an additional cost such as a kicker cost. This is true even if you use the mana to pay an additional cost while casting a spell "without paying its mana cost."
(wotc • 2018-12-07)
Rulings
The spell can't be countered if the mana produced by Cavern of Souls is spent to cover any cost of the spell, even an additional cost such as a kicker cost. This is true even if you use the mana to pay an additional cost while casting a spell "without paying its mana cost."
(wotc • 2023-11-10)
You must choose an existing creature type, such as Human or Warrior. Card types such as artifact can't be chosen.
(wotc • 2023-11-10)
You must choose an existing creature type, such as Human or Warrior. Card types such as artifact can't be chosen.
(wotc • 2018-12-07)
The spell can't be countered if the mana produced by Cavern of Souls is spent to cover any cost of the spell, even an additional cost such as a kicker cost. This is true even if you use the mana to pay an additional cost while casting a spell "without paying its mana cost."
(wotc • 2018-12-07)