The first chocker recoils from the Storm Burts, trying to fend off the effects with its tentacles, but receives the full effect never less.
Recovering the spell effects the First Choker releases Septa and attacks the Second Choker while the Second choker continues it's attacks upon the first:
First Choker Attack, left tentacle: 1d20 - 2 ⇒ (15) - 2 = 13
First Choker Attack, right tentacle: 1d20 - 2 ⇒ (19) - 2 = 17
Second Choker Attack, left tentacle: 1d20 - 2 ⇒ (6) - 2 = 4
Second Choker Attack, right tentacle: 1d20 - 2 ⇒ (14) - 2 = 12
First Choker damage, right tentacle: 1d4 + 3 ⇒ (1) + 3 = 4
While the first choker has minor wounds from the Storm Burst spell, the Second Choker is grievously injured by both the Storm Burst cast upon it as well as the strike from the other choker.
Septa, with a choker to either side of him, a bubbling spring to the left, open terrain to the right (with a stockade surrounding a cabin 25 feet away) and the tentacles of the two chokers whipping overhead as they attack each other, wonders what action to take.