It will not reduce waterbend costs that are additional costs for casting spells.
I primarily focused on Commander and Cube for these rankings
A basic land is often better in decks that run it
I was so focused on the life per card ratio that I ignored everything else going on in Necropotence

Ashad, the Lone Cyberman Ashling, the Limitless Astrid Peth Bag of Devouring Baloth Prime Biotech Specialist Blood Aspirant Blood Hypnotist Bloodbriar Body Dropper Burdened Aerialist Camellia, the Seedmiser Captain Lannery Storm Captain Lannery Storm Crime Novelist Desert Warfare Dina, Essence Brewer Dragon Appeasement Effluence Devourer Eloise, Nephalia Sleuth Esoteric Duplicator Evendo Brushrazer Experimental Confectioner Fleeting Memories Fleshtaker Forge Boss Furnace Celebration Giant Fly Gixian Infiltrator Gleaming Geardrake Gluttonous Guest Graf Mole Havoc Jester Hearthhull, the Worldseed Jenny Flint Juri, Master of the Revue Kels, Fight Fixer Kingpin, Wilson Fisk Korvold, Fae-Cursed King Lazav, Wearer of Faces Lightless Evangel Lonis, Genetics Expert Magnetic Snuffler Martha Jones Moonstone Eulogist Narci, Fable Singer Nuka-Cola Vending Machine Persuasive Interrogators Piper Wright, Publick Reporter Pirate Peddlers Popular Egotist Prowling Geistcatcher Rakdos, the Muscle Rapacious Guest Ravenous Squirrel Riveteers Ascendancy Rose, Cutthroat Raider Ruthless Deathfang Sandbender Scavengers Sanguine Brushstroke Sanguine Statuette Savra, Queen of the Golgari Scavenger's Talent Scouring Swarm Senator Peacock Sierra, Nuka's Biggest Fan Skittering Precursor Slaughter-Priest of Mogis Slayer's Bounty Smothering Abomination Sorcerer's Broom Szarel, Genesis Shepherd
