Greetings,
Since Storm Skills in general are themed around Vulnerable Damage and Druids will be able to equip Polearms, it should be possible to scale Vulnerable Damage and create a viable build. Currently, Druid is lacking in ways to scale Vulnerable Damage, most importantly the multiplicative variant, to be able to compete with the scaling of Critical Strike Damage. Therefore and unfortunately, Polearms will most likely not be considered using in Season 5 and will limit build diversity.
Below, a suggestion( take the exact numbers with a grain of salt) that is similar to Envenom:
Elemental Exposure: Lucky Hit: Your Storm Skills have up to a 10% chance to make enemies Vulnerable for 1/2/3 seconds. In addition, your inherent Vulnerable Damage Multiplier for Storm Skills is increased to x30.0%/x40.0%/x50.0% and you deal [+] 50% increased Vulnerable Damage.
Storm Skills having this increase in the Multiplier already gives a nice boost. If you want to gain even more power, simply add Vulnerable Damage to already existing uniques, for example: Greatstaff of the Crone(instead of non-physical), Unsung Ascetic’s Wraps(Added in the Unique power), Tempest Roar(instead of damage while shapeshifted).
Kind regards,
Supra