No seriously, so tell me what's broken then? We're not uber gamers so I am not expecting to see hordes of bloodletters or whatever else makes them broken.
Where to begin?
- Kairos: He has more spells than most armies have total spells (ie with multiple Lords and mages), he's close to unkillable, he owns the Magic phase more than Teclis.
- Heralds of Tzeentch: Horrors go to 4+ ward when you join the Herald with them. They are Level 2 Loremasters of anything. They are dirt-cheap and Heroes. They have Gifts to make them even better.
- Horrors: Units of T3 but cast like one Wizard with gun-magic from Lore of Tzeentch, the more powerful the spell requires a bigger unit. So, take a Life Herald, buff them to T8, and take a big horde. Regen casualties with 'Regrowth' and laugh.
It just gets stupider from there. Slanneshi units blenderise light-medium infantry. Khornate walks through magic and ends you with a billion S5 flaming close-combat attacks (Frenzy everywhere). Nurgle can be as destructive as regular nuke magic but with cheaper casting, and their infantry just refuse to die.
If, as you say, your friend is going to build a friendly list, you may stand a chance. If he doesn't optimise, doesn't load up on Tzeentch Heralds (insane not to but eh), yes you can take them down.
I'd talk things over with your opponent, so it's not one-sided. Better yet, grab the Daemon book and take a look at what he has on offer. It's mindbending just how OP even 'normal' Daemon lists are, because of their inbuilt advantages.
The general rule of thumb against Daemons is nuke them back (Shadow and Life nukes), and 'Lore of Light'. EOTG is also highly effective, as you hit at S5.
