User blog comment:LivesByProxy/Too Many Blades: Naming Conventions In League of Legends/@comment-26870289-20150927085349/@comment-24385282-20160128023449

Then again, Eviscerate communicates what does much better. Yes, he assaults you from the "shadows" (typically related with invisibility in LoL), but if its supposed to give any hint to how much pain you're about to face, Eviscerate works better, and sounds cooler, too. I didn't know exactly what the word meant, but it was pretty easy to figure out given the context.

And, like you say, League shouldn't be unclear, especially to newer players. But Shadow Assault basically relies on players knowing the connection betwen shadows and invisibility in the LoL naming scheme, whereas Eviscerate just needs you to know that getting eviscerated means taking a bajillion damage. If someone asked you to describe the names without really knowing what they meant, Shadow Assault would probably come across as someone jumping onto you from where you can't see them, or manipulating a shadow to attack you. The former is only part of what ult does, and honestly the less important part, and the latter is. Eviscerate would likely make people think "this guy is about to cut me up," so as soon as you see the blades pop out you know he's gonna try to 100-0 you in a few seconds.

I guess that's just my take on it, though, as clearly words that are more uncommon can be confusing to other players, especially ones who don't have English as their first language  (I think? Sorry if that's wrong, but that's how your comment comes across - "English is your mother language").