Soulstone Sanctuary

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.