For minor HP heal to self, you need to have bio gun equipped - press the white syringe to heal your self (button 5 on pc). This is your bio tactical skill. For full HP heal plus armor, while having any weapon equipped - you can hold the yellow syringe to heal your self (button 7 on pc). You can also tap to heal others. This needs ammo/charges which can be seen under the icon (0-3 max). This is your focus skill - note that it shares the same ammo with instant revives (where a bio attack revives a downed ally).
Good nice
I have a question, how do I use the syringe and fill my life in a matter of seconds?
For minor HP heal to self, you need to have bio gun equipped - press the white syringe to heal your self (button 5 on pc). This is your bio tactical skill.
For full HP heal plus armor, while having any weapon equipped - you can hold the yellow syringe to heal your self (button 7 on pc). You can also tap to heal others. This needs ammo/charges which can be seen under the icon (0-3 max). This is your focus skill - note that it shares the same ammo with instant revives (where a bio attack revives a downed ally).