Mods - Multiple

Hi, I know how to use mods alt/ctrl/shift and my current macro works perfectly. However, my question is about using a mod twice. I have a:

/castsequence [mod:shift] [InsertAblityONE], [InsertAbiltyTWO] in my keypress but I want another /cast [mod:shift] [InsertAbilityONE] in either my body or keyrelease.

Basically, this is what I’m trying to do.

/castsequence [mod:shift] Chains of Ice, Frostwyrm’s Fury

Problem is, when Frostwyrm is on it’s 3min cooldown, it wont let me cast Chains of Ice again. So I tried just adding in a /cast [mod:shift] Chains of Ice elsewhere, but it wont fire.

I’m currently using alt and ctrl, so I can’t spare those.

Any help is greatly appreciated.