Nixie

The singing comes up through the water, which is why it sounds the way it does - close, warm, and slightly wrong, like a voice heard through a wall. Nixies sing only where the water is deep enough to be worth the trouble. Millponds, river bends, the black stretch under a bridge. Shallow water gets nothing from them at all, and the villages that know this build their fords wide and keep the children off the banks.

The Song Below: 60 ft, and only from water at least a fathom deep. Save Wis Mind, fail save roll 1d6+1 psychic and the target moves to the water's edge and then into it, cooldown 2 rounds. Pull Down: bludgeoning, melee 5 ft, +2 to hit, 1d6+1, with Advantage against a creature already in the water.

Needs the Deep: it cannot sing, and will not fight, in water it cannot submerge in. Driven into the shallows it simply leaves. Bargainer: nixies keep bargains exactly and will trade a safe crossing, a drowned body or a lost thing from the riverbed for something they want, and what they want is rarely coin.