Hellouda
I remade the Rampage Inducer implemented in the modern zombies on my Kino map (I plan to add mutations like BO4 to make Rampage appear in my maps).
All done with commands only, no add-ons.
Rampage accelerates zombie spawning, increasing their speed between effect levels 1 and 2, and by round 15 they all have speed 3. Also, in the clip, I don't know if you noticed, but the rest period at the start of a round is much shorter with Rampage Inducer activated, like in the original zombies.
There are still sound effects missing for Rampage, and maybe some particle effects to add when you interact with it.