You are making me go through the code to prove it sure:
Here's the script for Vulkin's attack;
^ Do you want me to explain? I will
The "lightning" get faster over time because it it using
negative friction, which in GameMaker makes that continuous acceleration. Each bullet starts with a low speed (speed = 1) but gradually speeds up the longer it exist, however it is also depending on the global.firingrate, so if the firing rate is low, the friction is more negative −0.15 as you can see in the script. The moment he gets excited, he increases his own firing rate which makes the friction in the script more negative.