Artificial Lagoon

{t} to add {u} to you mana pool OR
{t} To roll a D20 and do the following
1-3 The glass is broken, sharks everywhere! Remove Artificial Lagoon from play
4-17 Artificial Lagoon is very popular add {u}{u} to your mana pool
18-20 Population boom, time to expand! Add a water token into play that is a copy of Artificial Lagoon.
The trick is to make it seem dangerous without losing any customers