How does the Bane spell interact with critical hits?

Question

The 1st-level spell bane (PHB, p. 216) allows you to curse a creature so that all of its saving throws and attack rolls are reduced by 1d4 for the duration:

Whenever a target [...] makes an attack roll or saving throw before the spell ends, the target must roll a d4 and subtract the number rolled from the attack roll or saving throw. (PHB 216)

How does the bane spell interact with a natural 20 on an attack roll?

I can see two possible interpretations:

• Bane is stronger: A target under the effect of bane cannot make critical attacks, because 20 - 1d4 will always be < 20.

• Critical is stronger: A target under the effect of bane can make crits, since crits occur on a natural 20, and the bane malus is applied after determining crit.

A good answer would include relevant rules text to show how this should be handled.

Answer 1

Bane has no bearing on a Critical Hit.

From page 194 of the PHB:

If the d20 roll for an attack is a 20, the attack hits regardless of any modifiers or the target’s AC. In addition, the attack is a critical hit, as explained later in this chapter.

Since a Critical Hit is determined by the roll of a natural 20, and not by the end result adding up to 20, any addition or subtraction (such as Ability Modifiers [as stated above] or spells such as Bane) to this roll doesn't matter, it is still a Critical Hit.

Also note that even if that were not the case, any creature that has +4 or higher bonus to the attack roll essentially counteracts the effects of Bane anyway.