This'll be my first time actually using a homebrew monster against my party, so I want opinions on it. It's meant to be minions for a level 6 underwater boss against a level 5 party (moderate encounter, but since it's underwater I'm treating it as severe).
N, small, elemental, aquatic, electricity
Perception +9
Skills Acrobatics +10, Stealth +9, Survival +9
Str +1, Dex +4, Con +3, Int -4, Wis +3, Cha +4
Electrical Movement (primal, electricity) The sea spark can move normally through an unwilling creature's space, but still can't end its turn there. When it does this, any creatures it moves through take 2d4 electricity damage (DC 19 basic Reflex save).
AC 19; Fort +6, Ref +12, Will +9
HP 36; Immunities bleed, electricity, paralyzed, poison, sleep; Resistances physical 5
Disperse (reaction) (electricity, evocation, primal); Trigger The sea spark takes damage. Effect After taking the damage, the sea spark Strides or Swims without triggering reactions. If the triggering damage was electricity or from a metal weapon, the damage dealt by Electrical Movement becomes 3d4 for this Stride or Swim.
Speed 25 feet, swim 35 feet
Melee (1 action) spark +10 (agile, electricity), Damage 1d8+6 electricity