Gather your ingredients.
Grind down the rub if it contained large pieces of herbs or ingredients that might become lodged in the needle.
Combine all of the ingredients in a saucepan, and bring to a simmer over medium heat for 5 minutes, stirring occasionally. Taste, and adjust your seasonings by adding more beef base and beer if needed.
Remove the saucepan from the heat and let the mixture cool for 15-20 minutes.
To use: draw up some of the mixture into the syringe, inject the meat and gradually release some of the marinade. The section will plump up a bit and there may be some spill over. Just mop it away and continue.
Discard any injection marinade that has come into contact with raw meat.
This recipe makes enough for 1 brisket, so double, triple, or quadruple the recipe based on your cooking needs.