Rampage: If the Zinogre takes more than 30 damage from one creature in one turn, it rampages. Its attacks deal an additional 1D6 lightning damage. Additionally, it make make another slam attack as part of it's multiattack action. Rampage ends if it takes more than 50 damage in a turn.

Electrical Charge: As an action, the Zinogre can charge its electricity, adding a charge point onto itself, to a maximum of 3. it's attacks deal an additional 1D6 lightning damage per point, it loses all of its Charge Points if it falls below half of its maximum health.

Multiattack: The Zinogre makes 2 Slam attacks (3 if rampaging)

Slam: Reach 10 ft, Single target. +9 to attack: On hit, 2D8+5 bludeoning.

Flying Slam: The Zinogre picks a point within 20 ft that it can see, it does a standing leap. every creature within 10 feet of that point must make a dexterity saving throw (DC 15) or take  28 (8D6) bludgeoning and fall prone, or half as much on a save, and they're not prone.

Charge: The Zinogre adds a charge point to itself, to a maximum of 3. 

Ball Lightning: The Zinogre spends a Charge Point, all creatures in a 60 foot line that the Zinogre can see must make a dexterity saving throw (DC 15) or take 18 (6D6) lightning damage, or half as much on a success.