Borderlands 3 Boss - How to defeat Mouthpiece at low level, Amara level 7 fight

Mouthpiece is a boss in Borderlands 3. He is located at Ascension Bluff in the Holy Broadcast Center.
Mouthpiece is the only loot source for the unique The Killing Word pistol and has an increased chance to drop the legendary Mind-Killer shotgun.
The fight have three different phases with increasing difficulty and different music. The boss is immune to damage for short time between phases.
Important: Ignore most of the tinks. Use them for second winds. If you have any kill skills, activate them first with one or two tinks. Use grenades, or anything else you can.

Borderlands 3 is an action role-playing first-person shooter video game developed by Gearbox Software and published by 2K Games. It is a sequel to 2012's Borderlands 2, and the fourth entry in the main Borderlands series.