Necromantic Aegis and Cast When Damage Taken

I'm trying to play around with an Occultist build supporting her own minions with auras and curses. I was wondering whether Cast when Damage Taken is viable for mass triggering spells (Frost Nova) when combined with Necromantic Aegis. With both gems on a linked shield.

My questions are: Will it trigger spells? Does the four second cooldown count for all minions or is it per each individual minion? Will my minions be damaged sufficiently to cast spells at a regular basis?

I am trying to test this out myself in Act 6, but so far it seems that it either doesn't work or my Frost Nombies kill everything before they receive enough damage.

Would love to hear if any of you knows more about this.

I don't think Necromantic Aegis does anything to socketed gems in the shield.

You still get the gems for yourself. Minions only get the shield, no gems.