These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Demonic Spiders: In Chapter 1, you have enemy Duskwalkers, who can who go behind front defenses, can do 80+ or 90+ damage an attack, are usually in the back two rows of the enemy formation, and are usually backed up and protected by Brawlers, Champions, Mammoth Riders, War Mammoths, and Skirmishers. In Chapter 2, you have to deal with the Silver Wolves, who do tremendous damage, have a lot of attacks that outright ignore Armor, and apparently give their Grenadiers nukes capable of dealing hundreds of damage to every one of your spaces at high enough levels.
And just in case you begin thinking that the Raiders are pushovers at this point, they come back even stronger (and dressed in black) later in Ch. 2. And they also give their grenadiers nukes.