Mai should've been happy that her deception worked, but she chided herself on being too slow with her spellcasting to interrupt the cultists' foolhardy leader. She allowed her elemental rage to build up within her, which she unleashed with the lightning storm she conjured on top of every cultist she could manage. A minor deluge ensued, making movement under the indoor stormcloud more difficult.
Minor action to use Promise of Storm, gaining +1 to attack rolls and +2d8+6 to damage with thunder/lightning powers UEMNT.
Standard action to use Ice Storm, converting to lightning per her paragon path, unfriendly area burst 3 centered at L19.
Int (implement) vs. Fort, and I'm guessing she has CA since they presumably can't see her.
Robed cultist1: (1d20+20)
And if he's still there, High cultist: (1d20+20)
lightning damage and the target is immobilized (save ends).
Miss: half damage and the target is slowed (save ends).
Effect: the burst creates a zone of difficult terrain that lasts until the end of the encounter.
Move action to shift 1 square to the left