Before i talk about this i would like to say this is a current MCLava feature, it would be pleasant if MCDzienny had added this feature:
We all love a good old lava survival, but in one round people found out the lava has been replaced with Water! Every-round theres a chance of lava being replaced too water for more fun. Their would also be a command to change it, As in, /watertolava and /lavatowater. Something like this. It would be very very fun and enjoying.