: This land becomes a 3/3 creature with vigilance and all creature types. It's still a land.
Soulstone Sanctuary's last ability doesn't have a duration. Once it resolves, it will remain in effect until the game ends, Soulstone Sanctuary leaves the battlefield, or some subsequent effect changes its characteristics, whichever comes first.
If this becomes a creature but you haven't controlled it continuously since your most recent turn began, you won't be able to activate its mana ability or attack with it that turn.
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: This land becomes a 3/3 creature with vigilance and all creature types. It's still a land.