Death Burst. When the eelfolk dies, it explodes in a burst of pent-up electricity. Each creature within 10 feet of it must make a DC 12 Dexterity saving throw, taking 7 (2d6) lightning damage on a failed save, or half as much on a successful one.
Hold Breath. The eelfolk can hold their breath for 1 hour.
Lunge. If the eelfolk move at least 20 feet straight toward a target and then hits with a long knife attack on the same turn, the target takes an extra 7 (2d6) piercing damage.
Ambusher. The hunter has advantage on attack rolls against any creature it has surprised.
Multiattack. The hunter makes two spear attacks
Spear. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 6 (1d8 + 2) piercing damage (two-handed melee) or 5 (1d6+2) piercing damage (range attack).
The Lunge Text reads: "If the eelfolk move at least 20 feet straight toward a target and then hits with a long knife attack on the same turn, the target takes an extra 7 (2d6) piercing damage"
I believe it should be the spear and not the long knife.
This looks like a copy and paste from the basic Eelfolk stat block where that one does have a long knife attached to it.