20 Minutes Till Dawn Synergies: How they work

Synergies are powerful upgrades that are unlocked when you have previously selected the required combination of upgrades. Most synergies require that two previous upgrades be chosen to unlock the ability to select the synergy. There are a total of 12 synergies with most requiring a total of two previous upgrades to be selected. The exception is Gun Mastery, which requires you to hold a total of three previous upgrades.