Tournament Grounds
Land
: Add 
.
: Add 
, 
, or 
. Spend this mana only to cast a Knight or Equipment spell.
No one knows when the tournament began. All they know is that it will never end.
Cristi Balanescu
Throne of Eldraine (ELD)
• #248Rulings
Mana produced by the second ability of Tournament Grounds can't be spent to activate abilities, including equip abilities.
(wotc • 2019-10-04)
If an effect refers to a “[subtype] spell,” it refers only to a spell that has that subtype. For example, Knights' Charge is a card with “Knight” in its name and benefits Knights, but it isn't a Knight card.
(wotc • 2019-10-04)
Rulings
Mana produced by the second ability of Tournament Grounds can't be spent to activate abilities, including equip abilities.
(wotc • 2019-10-04)
If an effect refers to a “[subtype] spell,” it refers only to a spell that has that subtype. For example, Knights' Charge is a card with “Knight” in its name and benefits Knights, but it isn't a Knight card.
(wotc • 2019-10-04)