Herald of purity - Randomly minions - Help

Hello there, I have some problems with my current build and need some help with it. First of all, my English isn't. So please feel free to correct me if I wrote something completely wrong :D.

Actually I'm playing a firestorm totem build as a Templar. And I wanted to try something new, for me. My plan is to go for the Guardian ascendancyand to push my high value with some more direct dmg. My solution was to go for firestorm totem + phantasm on kill support + herald of purity. The totems connected to the phantasm works really fine. The phantasm are triggered as it says. On kill and on hit at rare/unique enemies. Herald of purity now works just randomly but why? Sometimes I summon some minions out of it, sometimes not. And the tag with the hit on rare/uniques doesn't work at all. I turned off my Gerald of ash to see if it's maybe the burning dmg which let them spawn. But it isn't. Again Randomly here too. I wanted to support the firestorm with the support gem which gives a very high amount of spell dmg but can't trigger elemental ailments (actually forgot the name). If this support gem is socket to my firestorm totem, Herald of purity won't spawn any creatures for me. I've skilled the totem nod which turns my damage to zero. So there is no way that I have killed some creatures. I've also turned off the phantasm to see if there are triggering herald of purity. And again same result. Randomly spawns of minions. Maybe some one knows more about it than I do. Some help to this problem would be very nice. Thanks :)

My English isn't the best*