Can spellcasters try to make it difficult to identify what spell they're casting?

Question

How to identify a spell being cast? discusses how to identify a spell.

This question seeks to discover whether there are steps a spellcaster could take during casting to make this identification more difficult. The question is not about hiding the casting (such as casting the spell round a corner, then releasing it with a reaction) - the person trying to identify the spell has full view of the spellcaster casting it.

Such steps might include:

• Putting some irrelevant words around the actual mystic words of the verbal component
• Waving your hands as if performing a somatic component, despite the spell not having one

Is this sort of thing possible while casting a spell (to be clear, without any special capability such as the Sorcerer's Subtle Spell), and if so what effects does doing so have on spell identification?

Assume for the purpose of the question that the rules from Xanathar's Guide on spell identification are in use.

Answer 1

RAW, no.

For a caster who is required to use all components to a spell (Somatic, Verbal, or Material), there is no written mechanic to attempt to hide what is being cast.
In Xanathar's Guide to Everything p.85, rules for identifying a spell say "If a character can perceive the casting, the spells effect, or both, the character can make an Intelligence (Arcana) check with [their] reaction or action. The DC equals 15 + the spell's level." This should apply as a PC watching an NPC cast a spell, or as an NPC watching a PC cast a spell.

Rules designer Jeremy Crawford states on his twitter:

In Xanathar's, Identifying a spell requires an action or a reaction because it involves focused deduction; it's not automatic. Moreover, I didn't want combat to devolve into people identifying every spell.

By what he has written, a spell is already hard to identify, but a DM may homebrew this rule to instead mean a creature must spend a reaction or action to identify a spell due to all casters attempting to hide the spell being cast through some form of obfuscation, as you've mentioned.