Arcana of the Ancients, Homebrew
Electrocute. The accumulator can move through a space as narrow as 1 inch wide without squeezing. A creature that touches the accumulator or hits it with a melee attack while within 5 feet of it takes 5 ( 1d10 ) lightning damage. In addition, the elemental can enter a hostile creature's space and stop there. The first time the accumulator enters a creature's space on a turn, that creature takes 13 ( 3d8 ) lightning damage. This damage is also applied to any creature that starts its turn in the same space as the accumulator. Stormsheep. Metal armour makes any target particularly vulnerable to the accumulator. Take the AC total of the target provided from metal armor and subtract it from the target's AC. This is the to-hit number the accumulator needs to hit. Give the accumulator advantage if the target is wielding a metal weapon to the elementals attack roll. If the accumulator is hit by a living creature wielding a metal weapon, electricity leaps from the accumulator, connecting with the attacker's outstretched limb. It burns the attacker who must make a DC 15 INT saving throw or suffer a stroke, loses 3d6 INT points and falls unconscious until some of the target's INT ability drain is healed.
Multiattack. The accumulator makes two Lightning Slam attacks. Lightning Slam. Melee Weapon Attack: 1d20+8 to hit, reach 5 ft., one target. Hit: 14 ( 2d8+5 ) lightning damage, and the target is stunned until the end of his next turn as the accumulator draws out the charge from the target. Lightning Step. The accumulator disappears and reappears at any spot within 500 feet, as long as it has a line of sight to the area, or electricity could move via conduction from one area to the other.
Defensive Fission (Recharge after a Short or Long Rest). When attacked, the accumulator has a 45 percent chance to split into two creatures standing next to each other. The attacking character chooses which one to attack, but the attack has disadvantage. Both the original and the second accumulator have a hit point value equal to the accumulator at the time it split. Neither can reuse this ability until after a short rest.
Para-elemental plane of lighting, Plane of Air