Digimon Story Cyber Sleuth: Complete Edition – Efficient Grind Guide

Tactician USBs are equippable items that you can put onto any digimon. When that Digimon participates in the battle (meaning they can’t just be in the reserve slots), you’ll receive more EXP from that battle.
From my testing, One Tactician USB adds 100% EXP gain from a battle, meaning you get double the EXP you would’ve without it. Each Tactician USB works additively, which means with 3 Battle Digimon each equipped with 3 tactician USBs, you’ll have a bonus 900% EXP gain, or simply put 10x your usual EXP.

We’ll be trying to get 9 of these as soon as possible.

Tactician USBs are very rare drops from certain enemies such as PlatinumNumemon, and iirc you are only given a single one by playing the game normally and doing sidequests.
As such, the easiest method to obtain them are through the DigiFarm.

• A Rank 4 Farm, Preferrably Rank 5
• At least 150,000 Yen in currency – This will be used to purchase 10 Development Patches and 5 Developer Know-Hows.
• 10 Digimon to keep in the farm that you won’t be taking out

Firstly, you’ll want to set up a farm to use exclusively in the development of items.
Use Farm Expansion Plugins (which you’ll gain naturally by playing the game and through the various sidequests/cases that you’ll undertake) to rank up your farm to Level 4, and if possible, Level 5. This expands the amount of farm good slots that we can use to place Developer Know-Hows.

Next, prepare 10 Digimon. The type and level doesn’t matter, as they’ll just stay in the farm and be forced to perform grueling labor to produce USBs for you.
Now, check for their Personality traits! This is easiest done in the “Change Leader” menu on the DigiFarm, but can also be viewed in individual Digimon profiles.
We’re looking for Digimon with a Builder Personality, as that’ll increase the quality of items farmed through Development, and allow the production of Tactician USBs. We want all 10 Digimon on the Farm to be a Builder type though, so we’ll have to go buy some Development Patches to change the rest’s personality types.

Now we’ll have to first buy Development Patches, just enough for whichever Digimon aren’t Builder types on the farm.
They’re available for purchase at EDEN Entrance, so they can be bought at any point. Each costs 2500 Yen, which is basically chump change for now.

For the next step, we’ll need 4 or 5 Developer Know-How items, depending on your rank. They can be purchased at the store on the far right of the Digilab. Each one costs a hefty 25000 Yen, but it’s definitely worth it.

Now for the actual setup process:

We want to change every Digimon on the Farm to be a Builder Type personality through the use of Development Patches. You’ll have to move them to your party to do that first.
In the Farm Goods menu, fill the whole thing up with Developer Know-Hows. Now we’re all ready to go.

……
Tactician USBs can be gained from the 1000 Yen option, so start developing!
With this setup, it’ll take 20 minutes before an item is generated.
What item you get is completely up to RNG, which means your chances of getting Tactician USBs through this is actually quite small. However…

What you get from developing the items are not determined until right before the timer is over. As such, you can just start your own separate timer, (I’d recommend 18-19 minutes) and right when there’s about a minute left on the DigiFarm, save at the Digilab.
Mirei will send you an alert on what item your farm produced through the DigiLine. If it isn’t the Tactician USBs you wanted, exit to the game menu, and reload your save. Keep doing this until you get your Tactician USBs. Let me tell you, sometimes you get it the first try, and on others it takes you over twenty minutes of reloading and waiting a few seconds until it works.

Now just repeat this process up to four more times (as your farm will be producing two Tactician USBs at a time) and you’ll have the 9 Tactician USBs you need.
As a reminder, the timer at the farm seems to count down during anything as long as you’re not in a menu. Battling is fine, playing the game normally (like I did) is fine, etc.

This process can also be shortened with multiple farms with a similar setup, doing the same thing. If you’re planning on savescumming with multiple farms though, make sure they’re on a separate timer so you won’t have to hope for every farm producing Tactician USBs at the same time.

At this point, I’d probably say having all your main battle Digimon equipped with tactician USBs would be enough to just forget about grinding for the rest of the game. However, if you’re looking to Digivolve to a certain Digimon with very high ABI and stat requirements, I’d recommend you invest for the long term by making three PlatinumNumemon, as they have an EXP gain multiplier passive that stacks additively.
Leomon about to get beaten to death like in literally every other Digimon media.

As far as I know, there are two Digimon that give an EXP Bonus – PlatinumSukamon and PlatinumNumemon
PlatinumSukamon is a Champion Digimon, meaning you’ll be able to obtain it a lot earlier in the game. However, its passive is also a lot less substantial than PlatinumNumemon, a Mega Digimon’s.
Here’s a short chart on some Digivolutions that can result in PlatinumNumemon
I’d personally recommend Digivolving from Etemon or BlackKingNumemon, as they both learn Nightmare III, a powerful magic move, while SuperStarmon only learns physical attacks. Same goes for Digivolving straight from GoldNumemon. This is because PlatinumNumemon does NOT learn any magic attacks on its own, so you’ll need it to inherit those skills.
Here’s my personal recommendation for leveling a PlatinumNumemon from the ground up.

Once you’ve got your PlatinumNumemon, (preferrably 3 of them), equip them with 3 Tactician USBs each.

You should be getting about this much XP from a single battle now. Remember though, the EXP curve is exponential so you won’t be leveling up as much on higher levels. However, even at the 90s, you’ll still be leveling your digimon at least one level per battle.

This hacking skill, when activated, will instantly put you in a battle. No running around, just activate it. This tremendously speeds up grinding.
To unlock this ability, you’ll need to have a Rookie Free Type Digimon. I’d recommend Veemon For this, as he only takes up 5 memory and fulfills the conditions.
Veemon Digivolves from Tsunomon.

Honestly, this one completely depends on the current chapter you’re on. Usually the latest area you unlock has the strongest digimon you can face, which will also net you the highest EXP.
However, my recommendations are that you stick to an area that can easily access the Digilab to heal up your Digimons’ SP and Digivolve your various Digimon when needed.
One example would be the second area at the Vallhalla Server.