We use this primarily for RP and strategy purposes, "Here's a perfectly carved bust of our target." "Here's what the king sounds like." "Here's a 3D map with topography based on what I saw through my familiar's eyes, the enemies are Here, Here, aaaand Here" "This is what the creature we fought looked like." As a DM I'll sometimes run checks to see how accurate the caster can make it, but overall it's a handy tool and stays useful all the way through :)

Use Minor Illusion to create a topographical map, or a 3D rendering of the levels of a dungeon explored so far.

Instead of a crate, I usually have my character make a rising up motion with their hands and make the illusion a 5 ft cube of whatever the ground is made of. Now it looks like I used something like Mold Earth or something to raise the ground up to create a wall.

Minor illusion is also a fun way to flair your caster.  What kind of occluders do you use?  Walls of bones?  An impenetrable tangle of roses and thorns?  Or, yes, a crate.

Minor Illusion also means your Bard with Perfomance checks is their own 2 piece band.

Instead of waxworks or maniquines Cast it to make a suit of full plate striking a dynamic pose.

After the paladin dropped and the fighter drug her out of a room filled with baddies, my gnome warlock brought up the rear by retreating down a hallway and yelling “WALL OF POISON THORNS!” And used minor illusion to create a thorny bush. It not only granted cover but it served as an obstacle. Out of combat, he was constantly casting minor illusions to help illustrate his stories. I colored it as “paintings” he would create that hovered in the air, or small figurines on a board. The group called them my “PowerPoint” presentations :)

I recently used minor illusion for something I thought was pretty clever. I wanted to prevent a player from getting counterspelled (I was doing a combat test) so I had them create a spot of cover, hide behind it, and then cast their spell while obscured by the illusion. Since the other caster couldn't see them, they couldn't counterspell them.

If you're fighting an enemy with Counterspell, could you create an illusion of your own voice casting the verbal component of a high-level spell to try to trick them to waste their spell slots?

You should note that Intelligence is a monster dump stat, as is proficiency in investigation. Thus the chance for the foe to fail the check only gets better with your prof and Int. A CR 15 monster will likely have a 13 Int (+1) vs your DC 18.

You sort of hinted at one of my favorite combinations, Silent Image plus (auditory) Minor Illusion, on a Warlock.  
Being able to cast Silent Image at-will is an under-appreciated feature, especially when buffed up by auditory illusions. Silent Image can move, is larger and isn't limited to objects. Without Minor Illusion though, it's not nearly as strong.

I haven't tried this tactic yet, but I'm waiting to get the chance.  Cast fog cloud (preferably at a higher level to make a truly massive cloud).  Then use minor illusion to duplicate the sounds of my party members in combat.  I might be able to misdirect enemies who can't see their way through the fog.

An illusion of a wall with a loophole in it to see out of and fire arrows "through" could work for a player to hide behind for cover.  Visually this makes sense to give an enemy attacker a visual disadvantage on the attack, but it would actually do nothing physically.  So if the -5 to hit from 3/4 cover makes an attacker miss, it seems completely wrong, as an arrow would just go straight through the illusion.

This is addressed in the DMG page 272

HITTING COVER
When a ranged attack misses a target that has cover you can use this optional rule (yes I know this is an optional rule, keep reading) to determine whether the cover was struck by the attack. First, determine whether the attack roll would have hit the protected target without cover.  If the attack roll falls within a range low enough to miss the target but high enough to strike the target if there had been no cover, the object used for cover is struck.  

With that said, if the object being struck is an illusion it would not be struck and it would just hit the person hiding behind illusionary cover.  As a player I want so much to use Minor Illusion to allow my Gloomstalker Echo Knight to hide behind an illusionary bush will hit arrows all come out of his echo somewhere else.  As a DM Minor Illusion will never give an AC bonus for cover, only a visual advantage or disadvantage.

Chris, I was wondering how do you feel about this?  My thought was an enemy attacker would have disadvantage from visual obscurement , but the player behind the illusionary cover would not receive any bonus to AC because the cover is just an illusion.  Once the enemy hits the player, they would see through the illusion and no longer have disadvantage.

Additionally, I don't think an Echo Knight who is concealed, using a bow but having the arrow come from it's Echo should have it's position reveled.  I know this would be very overpowered being able to attack with advantage every turn, but logically there is no reason there position would be compromised.

I've recently started using minor Illusion to create a stylish and taller version of myself in a pose behind me during introductions.

your point that minor illusion at higher levels loses its "scaling" or effectiveness doesn't seem to make sense. True it doesn't do more, and your enemies might be more clever or have alternate senses, but against lets say high level grog like characters, it should still do what it has always done.

legit took me a minute to understand that you were saying "melee" and not "mah lay" i was like "wth is a mah lay character?"

Great video! I play a Shadow Monk and have been using Minor Illusion mainly for playing pranks and giving other characters exact visuals of things I've seen, but I dramatically underestimated the combat potential of this spell!

Now that an Illusionist Wizard can cast this as a Bonus Action, how would you change your tactical assessment of Minor Illusion? 🍻

The return of roll20 strategy! Love it.

Also useful outside combat. Showing maps, people & monsters, recorded messages, marking traps for others (there's your help action!). Used in bardic performances to show still screens of the scenes your describing or singing about.