Straight-forward: this question has caused an edit war and a close-reopen-close war. The argument for tagging and reopening is

The splat book only exists in DnD-5e, so it's not guessing – Pureferret

Can/should it be tagged as dnd-5e?

Related:

• What qualifies as guessing on a system?
• When is it OK to assume the system without it being considered a guess?
• Does adding the system tag to this question violate the "never guess the system" policy?
• What to do when an edit guesses the system being used rather than waiting for the querent to clarify?

And many more.