What build maximizes reach?

Question

A Bugbear (Long Limbed: reach +5 feet) wielding a reach weapon (10 feet of reach) can make a melee weapon attack with a reach of 15 feet.

If said Bugbear is a Battle Master with the Lunging maneuver, he can extend his reach of 5 feet for a single attack (achieving 20 feet of reach).

My question is: Can a player character's melee weapon reach be extended even further than that, or is 20 feet the absolute maximum?

Note that I'm searching for official non-playtest material; Unearthed Arcana would qualify as playtest material and be excluded. (Therefore currently excluding the "Giant Growth" Mystic Discipline from Unearthed Arcana).

If a spell/magic item/other can extend melee weapon reach (nonexistant example: "Scroll of Praying Mantis - Your arms grow bigger! You have more reach!"), it qualifies for the question. Material related to melee spell reach does not qualify.

Answer 1

There is some confliction in your question but I'll assume you want to make Melee Weapon Attacks at reach.

The highest reach would be 35 feet with a Giant-sized Bugbear Battlemaster Fighter/Way of the Four Elements Monk's unarmed strike whose flesh has been warped by an ichor-coated weapon. It costs 1 Superiority Die and 1 Ki point.

• Base reach is 5 feet
• Bugbear gives +5 feet
• a Potion of Giant Size gives +5 feet
• Lunging Strike (Fighter: Battlemaster) gives +5 feet
• Fangs of the Fire Snake (Monk: Way of the Four Elements) gives +10 feet
• In Avernus, weapons coated in demon ichor have the chance to warp flesh:

The target’s arms become tentacles with fingers on the ends, increasing its reach by 5 feet.

This combo works because of the Player's Handbook Errata, which changed future printings of the Player's Handbook. It reveals how the unarmed strikes can be used for the battlemaster's lunging strike.

Instead of using a weapon to make a melee weapon attack, you can make an unarmed strike ... You are proficient with your unarmed strikes.

Answer 2

As far as I can tell, you have gotten everything there is to get on this, barring polymorphing into creatures with longer reach. I built a character recently on this concept, and came up with the same design and conclusions you have.