Can a character with the Polearm Master feat make an opportunity attack against an invisible creature that enters their reach?

Question

The second benefit of the Polearm Master feat (PHB, p. 168) says:

While you are wielding a glaive, halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attack from you when they enter your reach.

The regular rules on opportunity attacks state:

You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach.

Obviously, Polearm Master lets you use your reaction to make an opportunity attack when a creature enters your reach, in addition to the opportunity attack any character can make when a creature leaves their reach. However, does the opportunity attack from Polearm Master follow the same restriction on needing to see the creature, or can this attack be made even without seeing the creature that enters its reach?

In other words, I'm asking whether the regular rule on opportunity attacks - specifically, the one about "a hostile creature you can see" - applies to the Polearm Master's opportunity attack as well, or whether it applies when any creature enters your reach (not just one you can see). Basically, does Polearm Master's new option change just the timing of the attack, or is it providing an entirely separate type of opportunity attack whose rules are wholly specified in the feat?

If an invisible creature enters the reach of a character with the Polearm Master feat, can the character make an opportunity attack against that creature?

Answer 1

The Polearm Master feat does not allow opportunity attacks against invisible creatures

My reasoning is that things that are named the same thing generally are the same game feature with the same rules. (I'm sure I've seen something stating this in a Crawford tweet or UA or something - even though the tweets are no longer "official" - but I can't remember where; it's not the "Combining Game Effects" rule, it was something else...)

The Polearm Master feat states that a creature moving into your reach can "provoke an opportunity attack"; it does not say that it causes any other kind of attack. Contrast this with the Barbarian Berserker's feature Retaliation:

Starting at 14th level, when you take damage from a creature that is within 5 feet of you, you can use your reaction to make a melee weapon attack against that creature.

It goes out of its way to describe an attack with a reaction rather than using the language of an opportunity attack. This implies that because Polearm Master does choose to use the term opportunity attack, it means the standard opportunity attack with all of the other rules attached to it, such as needing to see the creature, none of which is explicitly overridden in the feat's description. The feat merely provides a new way to trigger a standard opportunity attack.

Answer 2

The wording is fuzzy enough that you could interpret the sight requirement on the general rules for opportunity attacks as applying only to the general case and not to the specific case of Polearm Master. 5E is, at the same time, pretty good about noting restrictions like "creature that you can see", but it's also written to a looser standard of strictness and leaves more to the DM than other editions. So you could rule (or pitch it to your DM) either way.

But, as Ryan Thompson pointed out, reading it this way would indicate that the opportunity attack from Polearm Master also ignores other restrictions such as forced movement or teleportation, which leads to shenanigans.

And actually taking the option granted is usually a bad idea in its own right, for a few reasons:

• The attack is still against an unseen target, which imposes disadvantage at the very least.
• If the target is hiding (which they most likely became invisible to do in the first place), then you have to guess the location they're vacating, which can cause it to outright miss if you guess wrong (or, arguably, it can deny the attack completely because opportunity attacks target creatures, not locations).
• You're still spending your one reaction to take this substandard attack (unless you're combining it with Tunnel Fighter).