Hidden River Port

{t} Add {u} to your mana pool.
Mercantile: While this land is being tapped, if
you control three or more islands, you may Roll a die. If you roll 1-3 then choose one of the following.
1.) Gain 1 life.
2.) Deal 1 Damage to target creature.
3.) Draw a card.
This can only be used once per turn.
Only the best merchants know about the secret ports.