Use Genex Undine to search out Genex Controller. Summon Genex Controller and use it with Genex Undine to Synchro summon Hydro Genex. Since you already used up your normal summon to put Genex Undine on the field, you can use Double Summon to normal summon Genex Controller. Hydro Genex can be used to heal a lot of LP which is good in decks like Aromage or cards like The Winged Dragon of Ra and Neo-Parshath, the Sky Paladin.
Sends from your Deck to your Graveyard for cost / Adds from Deck to hand
If your opponent control a Special Summoned monter you can normal summon undine, mill atlantean marksman or heavy infantry, and add genex controller. Atlantean pop a card. Then play faustian bargain to send your opponent's special summoned monster and special summon genex controller you just added. Now you can synchro summon a lv 6 monster, or just attack with both for 2600 damage.
Pros : Because sending water monster to the graveyard is cost, it will still activated even when your opponent chain canadia or floodgate trap hole.
Cons : Is is UR, and the target water monster to mill is SR. Fml.