Upgrade your gems to infinity for the cost of a grade one gem

It's almost comically simple to blaze through the entire game using this easy keyboard shortcut.

The keyboard shortcut

• Create (2) grade 1 gems (I prefer bloodbound gems since they increase in damage with more kills)
  
• Put (1) gem in a tower, leave the other in your inventory
  
• Hover your cursor over the gem in the tower
  
• Press and hold the SHIFT key
  
• Press the B key while holding SHIFT
  
• Press the U key while holding SHIFT
  
• Alternate between pressing the B and U keys while holding SHIFT until you reach the desired gem grade

Keep in mind that this still costs 54 mana each time you upgrade.

If your mana pool is small, you won't be able to do this many times before you run out of mana. Think of it in terms of the rich getting richer: the bigger your initial mana pool, the more times you can do this at the start of a level. The gem that is being upgraded will be highlighted in your inventory, so make sure you're upgrading the one you actually want.

With this exploit, you'll be able to upgrade your gems to infinity for the cost of a grade one gem. You can then also complete every level in endurance mode on max difficulty with no trouble whatsoever, except the soreness of your fingers.

For more potential effectiveness, you can place amplifiers around your tower and enrage waves with gem bombs, though I haven't tried these out so I can't vouch for the real effectiveness of them. Each gem is maxed out at 48 shots per second on their own, so I like to have 2 gems on the field. Amplifiers can get around the shot cap.

[Chicken Alfredo From Domino's]

holy sh1t i just tried this and jesus christ what a cheat code... had some fun on a new save file but wont be abusing this on my main xD THANK YOU!

[Gernapious]

Oh this 100% works, to say it as simple as possible, make level one gems. Put one in a tower. Only point at the one in the tower. Hold shift and press B then release then press U and then release over and over.

[gerheart]

@Lord Admiral Revol Are you sure you're doing the input correctly? Holding shift while alternating pressing the B and U keys, starting with B? Do you have enough mana in your pool? It still costs 54 mana to do, the cost of upgrading a grade 1 gem. I just checked it, and it hasn't been patched. If it never worked, then how could I and many others do this exploit? I have a very strong suspicion you're just not doing it right.

[Lord Admiral Revol]

Nope, definitely either has been patched or never worked.

[Flim Flam the Zim Zam]

Yeah im just an idiot and didnt realise it leveled the one in the inventory, its definitely speeding things up

[gerheart]

@Flim Flam the Zim Zam I just checked and it hasn't been patched. I doubt Game in a Bottle ever will patch it.

[Flim Flam the Zim Zam]

Think this has been patched?

[Gleem]

Also, if you raise the gem level TOO HIGH, you'll start getting a weird error where enemies' health turns into NaN (not a number), and can no longer be killed.

[Gleem]

Okay, I've figured it out. I was doing it wrong. It's using the gem you're hovering over as the gem that determines the upgrade cost, and the gem in the side bar gets upgraded by +1 for that cost.

[Gleem]

I'm confused what exactly the exploit is then if you're just using mana to do an upgrade?