Tank Progression

The Expert Modifier unlocks only after meeting two requirements: you must have Hercules unlocked, and you must reach Modify Level 100 on the Upgrade tab (not the Modify/wrench tab). Once both conditions are met, the Expert Modifier button becomes available and you activate it manually by clicking it in the top-left corner of the Modify screen. It does not turn on automatically.

You can delay activation, but be very careful not to click it by mistake - once enabled, it cannot be deactivated. Expert Modifier lasts 30 minutes and applies to 100 upgrades only.

Start saving blueprints around Modify Level 90. Stop spending blueprints and stockpile everything you can. The blueprint goal before activation is roughly 200,000 blueprints. That should cover approximately 100 upgrades (~20 levels).

If you plan to use the Expert Modifier beyond Level 100, use this formula to estimate how many blueprints to save:

Example: if your current upgrade cost is 2,000 blueprints, prepare around 260k blueprints.