Castle Garenbrig enters tapped unless you control a Forest. {T}: Add {G}. {2}{G}{G}, {T}: Add six {G}. Spend this mana only to cast creature spells or activate abilities of creatures.
2019-10-04
Although the common lands have basic land types, they aren't basic lands.
2019-10-04
Once the common lands (such as Mystic Sanctuary) enter the battlefield tapped, there's no way to untap them with a spell or ability to make their last ability trigger.
2019-10-04
The mana generated by Castle Garenbrig's last ability can't be spent to activate abilities of creature cards that aren't on the battlefield.