My idea for this is something like Crusaders Crossbow, but deals half damage/heal up front, but with a DoT and HoT effect with total damage/heal done 125-150% of the Crusaders Crossbow. 1.5 times normal firing speed and 50% or 75% normal ammo.

I feel like the medi needs an option for multi target heals that doesn't rely on a taunt, like the Amputator, and I feel that a simple after effect could solve this. Also if a pyro can continue to burn targets then the medi should be able to have a syringe gun thats "dosage" continues to react in the targets body whether its continued heal or a poison effect in the opposing team.