Quick question - how does shove work?

When I try to shove a PC I get "they're too smart for that" but when I try to shove an NPC I get "You can't shove monsters".

Help file doesn't really explain what I'm doing wrong.

You need to be focused on an NPC and then shove the PC.

You can't shove NPC's and you can't shove PC's into other PC's

And you can't shove into servitors but you can into pets.

For example you are fighting the maran'tarabal and a paladin walks in you shove the paladin and then they are fighting the maran.

So how do familiars and zombies play in? Seems like with those limitations it's almost not worth doing. I had thought you could shove a conjurer into their servitors but I guess not?

Shoving into servitors tended to break the /entire/ conjurer class, and nightwalkers.

It was decided those two abilities were too important for shove to work and later changed.

I've never had the skill, but one time I took an army of animals against Jebaral (I think) and he shoved them all at me.

I don't know what pets it works on, but I'm assuming that is what it does/is used for. I had staff of conjuration animals and an animist spirit animal. All shoved at me, poor critters