As long as theyre milling more than 40 permanents (which is rather likely), they should die on the spot
White 1: Hushbringer Dies and enters-the-battlefield triggers are such a huge part of the format that Hushbringer will have an immediate and significant impact
(Choose any number of permanents and/or players, then give each another counter of each kind already there.) Lulu's first ability only cares about creatures attacking you, not planeswalkers you control or battles you protect
Anavolver Battlefield Forge Bloodfire Colossus Caves of Koilos Cetavolver Cromat Death Grasp Degavolver Desolation Angel Desolation Giant False Dawn Fervent Charge Fungal Shambler Gerrard Capashen Goblin Trenches Guided Passage Ice Cave Kavu Mauler Last Stand Legacy Weapon Lightning Angel Llanowar Wastes Mask of Intolerance Mystic Snake Necravolver Overgrown Estate Penumbra Wurm Pernicious Deed Phyrexian Arena Planar Despair Powerstone Minefield Prophetic Bolt Rakavolver Shivan Reef Spectral Lynx Spiritmonger Suffocating Blast Symbiotic Deployment Unnatural Selection Vindicate Whirlpool Warrior Wild Research Yavimaya Coast Yavimaya's Embrace
You could build it up as a Voltron commander and make use of this to commander damage your way to victory, or fill it up with other ways to dish out damage like Roiling Vortex and Guttersnipe
Id be very surprised if the type didnt get more support in the full Final Fantasy set, too.