In my brief experience, Naria seem to work better in a treefolk focused deck (FF KF), I haven't had much success myself (though considering my level that's not saying much). From observing other players I've only seen one person running Naria in an UD split and he got beaten pretty badly by the FW deck he was playing against.
I've just builded this BG, still zero pvp games with it (lack of time) so i can't bring any feedback. New narias bring to the BG two great ranged units (queens and mindtaps) and one great font contestor (ragevines). Other things are pretty the same as they used to be, just put in a rain of blood for the +3 aoe damage and foe the aoe bloodied: i run 4 champs with blood magic so with one rain i can refull them to full hp if they are near to 2-3 opposing champs.
