S+ is actually pretty hard to get

"Hard" suggests effort toward accomplishing a goal. The grades have no objective and verifiable utility, and so they are not a measure of accomplishment, but rather a functionally random assignment.

All you need is to farm well, ward, die less and you'll get that S+ in no time.

Source; I get a ton of S+'s with Morde. May be due to the fact that he mows down waves like it's nothin'

no it's not...

It's an S+, that's the idea.