To me, these upgrades are rather mediocre and not really worth it out of all the upgrades in Chaos. No one has ever tried getting it my game sessions. Has anyone found a significant use for them???

For me that was one of the niggles I had with the game, each God has their must-picks and their never-picks (like Horrors and Daemonettes). There really isn't much choice in what upgrades to pick, some are very good so you pick those, some are crap so you don't pick those.

I got the Daemonette upgrade on my first game. I haven't used it since, but I can understand the logic behind it. By making them practically indestructible, they can constantly work for your domination. It's kinda like the Bloodthirster upgrade in that sense. Considering Slaanesh has the least figures and no realistic way to draw extra cards, Pain & Pleasure can end up just doing too much for you. With 3 indestructible Daemonettes and the toughest greater daemon in the game, you're going to pretty much be set wherever you want to dominate.

Now, I've only seen the Horror upgrade used by bad players, and they never took advantage of it even then. It requires you to actively summon that round before you can claim the slot. Theoretically, it might have some use late in the game. Players will have an abundance of cards, and since they'll probably have a lot of figures on the board, they'll need to do something with their points. Regions could also get ruined, so card slots will be at a premium. Really though, it doesn't seem practical. You'd have to summon, hope nobody uses that other slot, and take the public one yourself. You're just broadcasting where you want to be, and that's not how Tzeentch works.

I suspect with a 5th power on the board it will be nearly impossible to avoid the old upgrades that normally get passed up. Conflict is going to be nearly impossible to avoid and with a 5th and card placement will be at a premium on the hotly contested areas. I hope this also means games will last a bit longer as well to see more upgrades getting thrown out. Although if that new Bloodletter preview card reads right Khorne is going to be a serious VP competitor now or will limit just how many cultists people are willing to put into play.