Avatar of Umberlee

Umberlee's Storm. A strong wind circles around the avatar. Any creature that moves or starts their turn within 10 ft. of the avatar must make a DC 12 Strength saving throw or be knocked prone.

Multiattack. The avatar can make 3 Slam attacks

Slam. Melee Weapon Attack: +12 to hit, reach 10 ft., 1 target. Hit: 17 (2d10 + 7) bludgeoning damage. 

Storm's Wrath (Recharge 5-6).  The avatar calls down a lightning barrage within 60 ft. of it.  Everything within a 15 ft. cylinder must make a DC 16 Dexterity saving throw or take 30 (6d10) lightning damage, or half as much damage on a success.

The Avatar can take 2 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Avatar regains spent legendary actions at the start of its turn.

Slam. The avatar makes a slam attack

Flood (Costs 2 Actions). The avatar turns into a flood of water.  The avatar can move up to its movement as a 20 ft. wide 5 ft. tall wave.  Any creature in its movement path must make a Dexterity saving throw or take 16 (4d8) bludgeoning damage, or half as much damage on a success.  At the end of this movement it reforms.