Unholy Sigils - unpredictable?

[Meowakin]

I'm having trouble figuring out what the deal is with this spell (Locus Ipsum Putesco). It seems to damage myself (and my pixies) reliably enough, but against mobs it seems to be hit or miss whether it will do anything. I'm having trouble figuring out the conditions for it to affect mobs, but so far all I can tell is that more often than not it does nothing to them.

[Meowakin]

Okay, I believe I identified this as being the spell not doing damage to enemies that cannot path to you easily. Which is unfortunate since I love the idea of trapping them with another spell first...

It probably also means it's an intentional design choice

[Meowakin]

You can probably close this unless it's not intended that it can't hit 'trapped' enemies. I've figured out how it actually works now to some great effect.

Side note it does not affect my familiars, but it does affect my summoned pixies. I assume druid familiars are intentionally immune to AoE and that's why they are unaffected, but it'd be nice if the pixies were immune too.