an arachnid boss mob

So, I say we need an arachnid boss mob because
a) it sounds cool
but b) Bane of Arthropods is currently worthless. 

Think about it... sharpness is good against pretty much anything and is an all-around useful enchantment, and smite is essential to dealing a sufficient amount of damage to the Wither, and 2 of 5 nighttime mobs are affected by smite. However, this leaves bane of arthropods in a pretty bad place. While its cousin enchantment smite is very strong against 11 hostile mobs, but bane of arthropods is only strong against a whopping 4 hostile mobs, all of which are really easy to kill with no additional damage enchantments. So, maybe we could solve this problem by adding an arachnid boss, maybe just a really big spider (although I don't really care), and it would be decently strong so that we have a genuine use for bane of arthropods. This also opens up a lot of other possibilities, such as maybe new effects, loot, drops. etc.